Thesis Sri Eka Wati 1b 19jan - Universiteit Twente · 2010-04-29 · Sri Eka Wati 08/276590/PMU/5638 AES-22612 Supervisor: Dr.rer. nat. Junun Sartohadi, M.Sc (UGM supervisor), Gadjah

UGMUGM

INTEGRATING LANDSLIDE SUSCEPTIBILITY INTOLAND CAPABILITY ASSESSMENT FOR SPATIAL PLANNING

A Case Study in Tawangmangu Sub District, Karanganyar Regency,Central Java Province, Indonesia

Thesis submitted to the Graduated School, Faculty of Geography, Gadjah Mada University andInternational Institute for Geo-information Science and Earth Observation in partial fulfilment of therequirements for the degree of Master of Science in Joint Education Program between Gajah MadaUniversity (UGM)-Yogyakarta-Indonesia and International Institute for Geo-information Science andEarth Observation (ITC)-Enschede-The Netherlands, on Geo-Information for Spatial Planning and RiskManagement

By:Sri Eka Wati

08/276590/PMU/5638AES-22612

Supervisor:Dr.rer. nat. Junun Sartohadi, M.Sc (UGM supervisor), Gadjah Mada University

Dr. David.G. Rossiter (ITC supervisor), Applied Earth Science, ITC

GADJAH MADA UNIVERSITY - INDONESIAINTERNASIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE

AND EARTH OBSERVATION – THE NETHERLANDS2010

I certify that although I may have conferred with others in preparing for this assignment, and drawnupon a range of sources cited in this work, the content of this thesis report is my original work.

Signed …………………….

Disclaimer

This document describes work undertaken as part of a programme of study at the Double DegreeInternational Program of Geo-information for Spatial Planning and Risk Management, a Joint EducationProgram of Institute for Geo-information Science and Earth Observation, the Netherlands and GadjahMada University, Indonesia. All views and opinions expressed therein remain the sole responsibility ofthe author, and do not necessarily represent those of the institutes

INTEGRATING LANDSLIDE SUSCEPTIBILITY INTOLAND CAPABILITY ASSESSMENT FOR SPATIAL PLANNING

A Case Study in Tawangmangu Sub District, Karanganyar Regency,Central Java Province, Indonesia

By:Sri Eka Wati

08/276590/PMU/5638AES-22612

Has been approved in Yogyakarta22 January 2010

By Team of Supervisors:

Chairman:

____________________________

External Examiner:

___________________________

Supervisor I

Dr.rer. nat. Junun Sartohadi, M.Sc

Supervisor II

Dr. David.G. Rossiter

Certified by:Program Director of Geo-Information for Spatial Planning and Risk Management

Graduate School Faculty of Geography, Gadjah Mada University

Dr. H.A Sudibyakto, M.S.

INTEGRATING LANDSLIDE SUSCEPTIBILITY INTO LAND CAPABILITY ASSESSMENT FOR SPATIAL PLANINGA CASE STUDY IN TAWANGMANGU SUB DISTRICT, KARANGANYAR REGENCY, CENTRAL JAVA PROVINCE

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ABSTRACT

Land capability assessment is one of the important points in spatial planning. The assessment isconducted to divide the land into three land use functions (protected, buffer, and cultivated area) and tomanage further land use. The present land capability analysis utilizes scoring method from Ministry ofAgriculture. This method considers erosion hazard associated with soil type. Since Tawangmangu SubDistrict is also prone to landslide hazard, the landslide susceptibility information shall be taken intoaccount in land capability. This research is focused on the integration process of landslide susceptibilityin land capability assessment.

Landslide susceptibility was analyzed by means of heuristic approach (weighted score method).The parameters were slope, lithology, soil depth, texture, permeability, and land use. The weight wasderived from pair wise method and the score was generated from rank method. Those methods areavailable in ILWIS. A proposed land capability classification was developed based on USDA approach.The susceptibility information was integrated as one additional constraint factor in proposed method.The land capability assessment was developed in general and detailed version. The obtained landcapability class was harnessed for dividing land use function and identifying land use deviation. Landcapability analysis by means of scoring method was also done in order to compare the obtained result.

More than one third of study area (42%) is categorized as high and very high susceptible tolandslide while 43% of total area is classified as moderate susceptible area. The rest is categorized aslow susceptible area. General land capability classes for study area are class IV, VI, VII, and VIIIwhereas the detailed land capability class consists of class III, IV, V, VI, VII, and VIII. General landcapability class classifies more than a half of study area (58%) as protected area, 31% is assigned asbuffer area, and 11% is apportioned as cultivated area. Besides, detailed land capability class allocates55% of study area as protected area, 37% as buffer area, and 8% as cultivated area. Moreover, the landuse deviation in buffer area is higher than protected area and there is no land use inexpediency incultivated area. On the other side, general version of scoring method assigns 51% of total area asprotected area; 31% as buffer area and 18% as cultivated area whereas the proportion of protected,buffer, and cultivated area based on detailed version is 38%, 45% and 17% respectively. Scoringmethod also identifies that most land use divergence occurs in buffer area rather than protected andcultivated area.

Key Words: Landslide, Land Capability, Spatial Planning


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ACKNOWLEDGEMENT

A lot of people are implicated during this research. Their valuable supports and contributionsmake me stronger to do the best effort for this research. I would like to dedicate high achievement formany people who accompanied me to pass the hardest time and helped me to successfully complete thisresearch.

First of all, praises to Allah swt. He gives me extra ordinary life with a lot of blessing. God isguiding me all the time and revealing the brave to survive in any unpredictable situation. His greatpower conveys me to reach my dream.

I would like to give gratefully respect for two excellent supervisors, i.e. Dr.rer.nat. JununSartohadi, M.Sc (UGM supervisor) and Dr. David G. Rossiter (ITC supervisor). They work hard toguide me step by step, to placidly teach me the new knowledge, and to make sure that I am still on thetrack.

Special thank is committed to related parties in MSc Double Degree Program of Geo-Information for Spatial Planning and Risk Management, Dr. H. Sudibyakto (UGM Course Coordinator),Drs. Robert Voskuil (ITC Course Coordinator), and all the lectures both in UGM and ITC. Thisprogram has improved my skill and knowledge in the subject of disaster and planning.

Next achievement is granted to BAPPENAS and NESO. Those institutions have given me theopportunity in pursuing my education in Indonesia and Netherland. Their supports in fully funding ofmy study present many interesting experiences, particularly in Netherland.

Great thanks are consigned for several institutions in Karanganyar Regency and TawangmanguSub District which support the required data for this research. Those institutions are Development andPlanning Board (BAPPEDA), National Unity and Community Protection (KESBANGLINMAS),Center of Statistical Bureau (BPS), Public Work (PU), Sub District Office, and Village Offices inTawangmangu Sub District.

I devote this thesis for the beloved people in my life, my parents (Slamet Sukamto andMudjinem) and my young sister (Dwi Astuti, A.Md). Your patient, support, and guidance are the mostvaluable thing for my life. You always encourage me to come up my dream and to do anything as bestas I can. Never give up in facing the problem is the key. I love you all. Especially for my soul mate, thebest man in my life, Deddy Agus Susanto, S.T, your supports and sacrifices in accompanying me duringthis research represent how deep you love me. For Deddy’s parent and his young brother, I would liketo say grateful thank for your support during my study.

Many thanks are finally assigned to all my classmates, my big family in Yogyakarta, mycolleagues in BAKOSURTANAL, my friends in Netherlands, my friends in Geography- University ofIndonesia and Gadjah Mada University, and other people who cannot be mentioned individually.

Yogyakarta, January 2010

Sri Eka Wati


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CONTENTSPage

Abstract……………………………………………………………………………………………... iAcknowledgement…………………………………………………………………………………... iiContents……………………………………………………………………………………………... iiiList of Figures………………………………………………………………………………………. vList of Tables………………………………………………………………………………………... viiList of Abbreviation………………………………………………………………………………… ix

Chapter 1. Introduction……………………………………………………………………………... 11.1. Background…………………………………………………………………………………….. 11.2. Problem Statement……………………………………………………………………………... 11.3. Objectives………………………………………………………………………………………. 21.4. Research Questions…………………………………………………………………………….. 21.5. Thesis Structure………………………………………………………………………………… 31.6. Significance of the Research…………………………………………………………………… 31.7. Scope and Limitation……………………………………………………………………........... 3

Chapter 2. Literature Review……………………………………………………………………….. 42.1. Natural Hazard…………………………………………………………………………………. 42.2. Landslide……………………………………………………………………………………….. 42.3. Landslide Susceptibility………………………………………………………………………... 52.4. Spatial Planning and Hazard…………………………………………………………………… 62.5. Spatial Planning in Indonesia…………………………………………………………………... 72.6. Land Capability on Spatial Planning in Indonesia……………………………………………... 82.7. USDA Land Capability Classification ………………………………………………………… 10

Chapter 3. Study Area and Research Method………………………………………………………. 163.1. Study Area……………………………………………………………………………………… 16

3.1.1. Geographical Location………………………………………………………………….. 163.1.2. Geomorphological Conditions………………………………………………………….. 163.1.3. Geological Conditions…………………………………………………………………... 193.1.4. Land Use………………………………………………………………………………... 213.1.5. Rainfall Intensity…………….………………………………………………………….. 233.1.6. Soil Characteristics……………………………………………………………………... 233.1.7. Demographic Conditions……………………………………………………………….. 23

3.2. Method…………………………………………………………………………………………. 243.2.1. Data Preparation/Data Collection………………………………………………………. 243.2.2. Data Processing……………………….………………………………………………… 283.2.3. Data Analysis…………………………………………………………………………… 303.2.4. Equipment and Software………………………………………………………………... 30

Chapter 4. Landslide Susceptibility of Tawangmangu Sub District………………………………... 314.1. Introduction ……………………………………………………………………………………. 314.2. Landslide Events in Tawangmangu Sub District……….……………………………………… 314.3. Landslide Type in Tawangmangu Sub District ……………………………………………….. 334.4. Development of Landslide Susceptibility Information………………………………………… 344.5. Landslide Susceptibility Zone……………..…………………………………………………… 384.6. Settlement Area in Landslide Susceptibility Zone……………………………………………... 384.7. Existing Landslide Mitigation Strategies………………………………………………………. 424.8. Proposed Landslide Mitigation Strategies……………………………………………………... 42

4.8.1. Local Government Strategies…………………………………………………………… 434.8.2. Local Community Strategies……………………………………………………………. 44

Chapter 5. Land Capability Assessment of Tawangmangu Sub District…………………………… 455.1. Introduction……………………………….……………………………………………………. 45


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5.2. Land Capability Assessment Developed by Local Government………………………………. 455.3. Proposed Land Capability Classification………………………………………………………. 465.4. General Land Capability Class Based on Proposed Method……………………...…………… 475.5. Detailed Land Capability Class Based on Proposed Method…………………………………... 565.6. The Other Alternative in Land Capability Assessment………………………………………… 59

Chapter 6. Land Use Function of Tawangmangu Sub District …..………………………………… 616.1. Introduction…………………………………………………………………………………….. 616.2. Land Use Function Developed by Local Government…………………………………………. 616.3. Development of General Land Use Function…………………………………………………... 63

6.3.1. General Land Use Function Based on Ministry of Agriculture’s Method (ScoringMethod)………………………………………………………………………………………... 636.3.2. General Land Use Function Based on Proposed Method………………………………. 646.3.3. The Comparison of General Land Use Function Developed by Scoring and ProposedMethod………………………………………………………………………………………… 65

6.4. Development of Detailed Land Use Function…………………...……………………………... 676.4.1. Detailed Land Use Function Based on Ministry of Agriculture’s Method (ScoringMethod)……………………………………………………………………………………....... 676.4.2. Detailed Land Use Function Based on Proposed Method……………………………… 676.4.3. The Comparison of Detailed Land Use Function Developed by Scoring Method andProposed Method……………………………………………………………………………… 68

Chapter 7. Land Use Deviation in Tawangmangu Sub District…………………...……………….. 707.1. Introduction…………………………………………………………………………………….. 707.2. The Suitability between Land Use Function and Land Use Practice…………………………... 707.3. The Identification of General Land Use Deviation…………………...……..………………… 71

7.3.1. General land Use Deviation Based on Scoring Method.……………….………………. 717.3.2. General land Use Deviation Based on Proposed Method.……………………………… 72

7.4. The Identification of Detailed Land Use Deviation……………………………………………. 747.4.1. Detailed Land Use Deviation Based on Scoring Method.…...………............................. 747.4.2. Detailed Land Use Deviation Based on Proposed Method.…………………………….. 75

7.5. The Cause of Land Use Deviation…………………………………………………………...… 777.6. The Application of the Result of the Research on Spatial Planning…………………………… 78

Chapter 8. Conclusions and Recommendations…………………………………………………….. 808.1. Conclusions…………………………………………………………………………………….. 808.2. Recommendations……………………………………………………………………………… 80

References…………………………………………………………………………………………... 82

Appendix…………………………………………………………………………………………… 85Appendix 1. Field Data……………………………………………………………………………... 86Appendix 2. Slope Map Based on Ministry of Agriculture’s Method and Soil Type Map………… 87Appendix 3. Monthly Rainfall Intensity……………………………………………………………. 88Appendix 4. Documentation of Field Work Activity……………….………………………………. 91


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LIST OF FIGURESPage

Figure 1.1. Thesis Structure……………………………………………………………………….. 3Figure 2.1. Landslide Types………………………………………………………………………. 5Figure 2.2. Soil Texture Chart…………………………………………………………………….. 12Figure 2.3. Chart for Estimating Proportions of Coarse Fragments and Mottles…………………. 13Figure 3.1. SRTM of Java Island………………………………………………………………….. 16Figure 3.2. Ikonos Image of Tawangmangu Sub District………………………………………… 16Figure 3.3. Administration Map of Tawangmangu Sub District……………………………….…. 17Figure 3.4. Landform Map of Tawangmangu Sub District …………………….………………… 17Figure 3.5. Limestone hill ………………………………………………………………………... 20Figure 3.6. Fault from Southward to Westward which Separates Old Lawu Volcano and YoungLawu Volcano…………………………………………………………………………………….. 20Figure 3.7. Geological Map of Tawangmangu Sub District……..………..……………………… 21Figure 3.8. Land Use Map of Tawangmangu Sub District………..……...………………………. 22Figure 3.9. Vegetable Garden in Hilly Area………………………………..……………………... 22Figure 3.10. Settlement in Undulating Terrain Area……………...……..………………………... 22Figure 3.11. Pine Trees in Front Slope of Lawu Volcano Area…………………………………... 22Figure 3.12. Mixed Garden at Moderate Hill in Sidoramping Lava……………………………… 22Figure 3.13. Paddy Field at Low Hill in Volcanic Rock Formation……………………………… 22Figure 3.14. Monthly Rainfall Intensity Chart……………………………………………………. 23Figure 3.15. Research Flowchart………………………………………………………………….. 25Figure 3.16. Soil Sample Distribution Map of Each Landform in Tawangmangu Sub District … 27Figure 4.1. Landslide in Ngledoksari Sub-Village………………………………………………... 31Figure 4.2. The Number of Landslide Events in Each Village…………………………………… 31Figure 4.3. The Remnant of Landslide Evidence in Ikonos Image……………………………….. 31Figure 4.4. Damaged Agricultural Land (Mixed Garden) in Bandardawung Village…..………… 32Figure 4.5. Damaged Agricultural Land (Vegetable Garden) in Kalisoro Village…..…………… 32Figure 4.6. Damaged Houses and Road in Tengklik Village……………………………………... 32Figure 4.7. Repaired House Because of Landslide in Sepanjang Village………............................ 32Figure 4.8. Direction of Landslide and Susceptible House in Sepanjang Village………………... 32Figure 4.9a. Damaged Road due to Landslide in Karanglo Village………………………………. 32Figure 4.9b. Direction of Landslide and Susceptible House in Karanglo Village………………... 32Figure 4.10. Landslide Events Map of Tawangmangu Sub District……………………………… 33Figure 4.11. Rotational Landslide Scheme………………………………………...……………… 33Figure 4.12. Rotational Landslide in Bandardawung Village…………………………………….. 33Figure 4.13. Slope Stability Diagram……………………………………………………………... 34Figure 4.14. Slope Map of Tawangmangu Sub District…………………………………………... 36Figure 4.15. Soil Depth Map of Tawangmangu Sub District………...…...……………………… 36Figure 4.16. Soil Texture Map of Tawangmangu Sub District…………………………………… 37Figure 4.17. Soil Permeability Map of Tawangmangu Sub District……………………………… 37Figure 4.18. Landslide Susceptibility Map of Tawangmangu Sub District……………………… 39Figure 4.19. Settlement Area in Hillside in Bandardawung Village……………………………… 40Figure 4.20. Settlement Area below The Road in Blumbang Village…..………………………… 40Figure 4.21. Settlement Area in Hillside in Tawangmangu Village….……………………….….. 40Figure 4.22. Map of Settlement Area Distribution in Landslide Susceptibility Zone ofTawangmangu Sub District……………………………………………………………………….. 41Figure 4.23. Landslide Warning Sign in Tengklik Village……………………………………….. 42Figure 4.24. Landslide Early Warning Tool in Ngledoksari Village……………………………... 42Figure 4.25. Landslide Susceptibility Map of Tengklik Village………………………………….. 42Figure 4.26. Retaining Wall in Collector Road between Karanganyar Regency and MagetanRegency…………………………………………………………………………………………… 42Figure 4.27. Landslide Information Board in Tengkik Village…………………………………… 42Figure 5.1. Land Capability Map Developed by Local Government in Regency Scale………….. 46Figure 5.2. Erodibility Index Map of Tawangmangu Sub District……………………...………... 50Figure 5.3. Actual Erosion Map of Tawangmangu Sub District………………………………….. 50


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Figure 5.4. Soil Drainage Map of Tawangmangu Sub District………………………………….. 53Figure 5.5. Rock Fragment Map of Tawangmangu Sub District …………………………............ 53Figure 5.6. Land Capability Map of Tawangmangu Sub District………………………………… 55Figure 5.7. Flowchart of Detailed Land Capability Assessment………………………………….. 57Figure 5.8. Detailed Land Capability Map of Tawangmangu Sub District.…..…………………. 58Figure 5.9. Flowchart of an Alternative Method……..…………………………………………… 59Figure 5.10. Land Capability Map of Tawangmangu Sub District Based on AlternativeMethod………………………………………………………………………………..................... 60Figure 6.1. Allocation Map of Protected Area in Regency Scale………………………………… 62Figure 6.2. Allocation Map of Cultivated Area in Regency Scale………………………………... 62Figure 6.3. General Land Use Function Map of Tawangmangu Sub District Based on Ministryof Agriculture’s Method…………………………………………………………………………... 66Figure 6.4. General Land Use Function Map of Tawangmangu Sub District Based on ProposedMethod…………………………………………………………………………………………….. 66Figure 6.5. Detailed Land Use Function Map of Tawangmangu Sub District Based on Ministryof Agriculture’s Method…………………………………………………………………………... 69Figure 6.6. Detailed Land Use Function Map of Tawangmangu Sub District Based on ProposedMethod…………………………………………………………………………………………….. 69Figure 7.1. General Land Use Deviation Map of Tawangmangu Sub District Based on Ministryof Agriculture’s Method……........................................................................................................... 72Figure 7.2. General Land Use Deviation Map of Tawangmangu Sub District Based on ProposedMethod…..………………………………………………………………………………………… 73Figure 7.3. Detailed Land Use Deviation Map of Tawangmangu Sub District Based on Ministryof Agriculture’s Method…..………………………………………………………………………. 75Figure 7.4. Detailed Land Use Deviation Map of Tawangmangu Sub District Based onProposed Method….……………………………………………………………...……………….. 77Figure 7.5. Proportion Chart of Present Settlement Area in Each Slope Class…………………… 78


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LIST OF TABLESPage

Table 1.1. Research Questions Associated with Specific Objectives…………………………….. 2Table 2.1. Some Potentially Hazardous Environmental Elements or Events……………………... 4Table 2.2. Classification of Landslides…………………………………………………………… 5Table 2.3. Slope Classification…………………………………………………………………… 9Table 2.4. Soil Type Classification……………………………………………………………….. 9Table 2.5. Average Daily Rainfall Intensity Classification………………………………..……… 9Table 2.6. USDA Slope Classification……………………………………………………………. 10Table 2.7. Soil Structure Classification…………………………………………………………… 11Table 2.8. Soil Permeability Classification……………………………………………………….. 11Table 2.9. Erodibility Index Classification………………………………………………………... 11Table 2.10. Actual Erosion Classification………………………………………………………… 12Table 2.11. Soil Depth Classification……………………………………………………………... 12Table 2.12. Soil Texture Classification…………………………………………………………… 12Table 2.13. Soil Permeability Classification……………………………………………………… 12Table 2.14. Soil Drainage Classification………………………………………………………… 13Table 2.15. Classification of Rock Fragment in the Soil ………………………………………… 13Table 2.16. Classification of Stone on the Surface……………………………………………..… 13Table 2.17. Classification of Rock on the Surface……………………………………………...… 14Table 2.18. Classification of Flood Threat………………………………………………………... 14Table 2.19. Classification of Salinity……………………………………………………………... 14Table 2.20. Land Capability Classification……………………………………………………….. 15Table 2.21. Land Capability Class Description…………………………………………………… 15Table 3.1. Width Area of Each Slope Class………………………………………………………. 16Table 3.2. Land Use of Tawangmangu Sub District……………………………………………… 21Table 3.3. Montly Rainfall Intensity of Tawangmangu Sub District……………………………... 23Table 3.4. Population Data of Tawangmangu Sub District………………………………………. 24Table 3.5. Data Requirement……………………………………………………………………… 26Table 3.6. The Number of Samples for Each Landform………………………………………….. 27Table 3.7. The Comparison Method of General and Detailed Version in land CapabilityAssessment………………………………………………………………………………………... 29Table 3.8. Correlation between Land Capability and Land Use………………………………….. 29Table 3.9. The Difference of General and Detailed Version in Land Use Function Division……. 30Table 4.1. Landslide Events in Tawangmangu Sub District……………………………………… 32Table 4.2. The Weighted and Score of Landslide Susceptibility Parameters…………………….. 35Table 4.3. The Width Area of Landslide Susceptibility Class……………………………………. 38Table 4.4. Land Suitability Criteria for Settlement Purpose……………………………………… 40Table 4.5. Distribution of Settlement Area in Each Landslide Susceptibility Class……………… 41Table 4.6. List of Plants for Strengthening the Soil………………………………………………. 44Table 5.1. Classification of Land Capability Parameters in RTRW…...…………………………. 45Table 5.2. Proposed Land Capability Classification……………………………………………… 47Table 5.3. Erodibility Index Based on Soil Type and Geological Formation…………………….. 48Table 5.4. Erodibility Index Based on Soil Type…………………………………………………. 48Table 5.5. Erodibility Class for Each Landform………………………………………………….. 49Table 5.6. Actual Erosion Class for Each Landform……………………………………………… 51Table 5.7. General Land Capability Class and Subclass for Tawangmangu Sub District………... 54Table 5.8. Detailed Land Capability Class Based on Proposed Method…...……………………... 57Table 5.9. Land Capability Class Based on Alternative Method…………………………………. 59Table 6.1. Land Use Function Based on Ministry of Agriculture’s Method……………………… 63Table 6.2. Land Use Function Based on Proposed Method………………………………………. 64Table 6.3. General Land Use Function Comparison …………..…………………………………. 65Table 6.4. Distribution of Detailed Land Use Function Based on Ministry of Agriculture’sMethod…………………………………………………………………………………………….. 67Table 6.5. Distribution of Detailed Land Use Function Based on Proposed Method…………….. 68Table 7.1. The Suitability between Land Use and Land Use Function ……………...…………… 71


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Table 7.2. The Width Area of General Land Use Deviation Based on Scoring Method.…..…….. 72Table 7.3. The Width Area of General Land Use Deviation Based on Proposed Method.…..…… 73Table 7.4. The Width Area of Detailed Land Use Deviation Based on Scoring Method..….......... 74Table 7.5. The Existence of Detailed Land Use Deviation Based on Scoring Method in EachVillage…………………………………………………………………………………………….. 75Table 7.6. The Width Area of Detailed Land Use Deviation Based on Proposed Method..……… 76Table 7.7. The Existence of Detailed Land Use Deviation Based on Proposed Method in EachVillage…………………………………………………………………………………………….. 76


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LIST OF ABBREVIATION

AMSL Above Mean Sea LevelBAKOSURTANAL Badan Koordinasi Survei dan Pemetaan Nasional

National Coordinating Agency for Surveys and MappingBAPPEDA Badan Perencanaan dan Pembangunan Daerah

Development and Planning BoardBNPB Badan Nasional Penanggulangan Bencana dan Pengungsi

National Agency for Disaster Tackling and RefugeeBPS Badan Pusat Statistik

Center of Statistical BureauDEM Digital Elevation ModelFAO Food and Agriculture OrganizationGIS Geographic Information SystemICIMOD International Center for Integrated Mountain DevelopmentILWIS Integrated Land and Water Information SystemITC International Institute for Geo-information Science and Earth ObservationKESBANGLINMAS Kesatuan Bangsa dan Perlindungan Masyarakat

National Unity and Community ProtectionLCLP Land Capability and Land Use PlanningPerda Peraturan Daerah

Regional RegulationPUSLITBANG GEOLOGI Pusat Penelitian dan Pengembangan Geologi

Geological Research and Development CenterPVMBG Pusat Vulkanologi dan Mitigasi Bencana Geologi

Centre of Volcanology and Geological Disaster MitigationRDTRK Rencana Detail Tata Ruang Kota Kecamatan

Detailed Spatial Plan of Subdistrict CityRTRW Rencana Tata Ruang Wilayah

Regional Spatial PlanRUTRK Rencana Umum Tata Ruang Kota Kecamatan

General Spatial Plan of Subdistrict CitySRTM Shuttle Radar Topographic MissionUGM Universitas Gadjah Mada

Gadjah Mada UniversityUNISDR United Nation-International Strategy for Disaster ReductionUSDA United States Department of AgricultureUSGS United States Geological SurveyUTM Universal Transverse MercatorUUPA Undang Undang Pokok Agraria

The Basic Agrarian Law ActWTU Wilayah Tanah Usaha

Exertion Land Region


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CHAPTER IINTRODUCTION

Introduction chapter describes the background of this research. The problem statement emphasizes theactual problems in the study area. Those problems are elaborated in four specific objectives and nineresearch questions. This chapter also includes thesis structure, significant of the research, and alsoscope and limitation.

1.1. BackgroundHazards can be defined as a potentially damaging physical event, phenomenon or human

activity. The hazards may cause the loss of life or injury, property damage, social and economicdisruption or environmental damage (UNISDR, 2009). The damages and disruptions are concerned withthe magnitude of the hazard and the number of elements at risk.

One of the common hazards is landslide. Landslide is described as a wide variety process that isresult in the downward and outward movement of slope-forming materials. The materials includingrock, soil, artificial fill, or a combination of these may move by falling, toppling, sliding, spreading, orflowing caused by gravitational forces (Marfai, 2006). Landslide happens as a result of combinedpreparatory and triggering factors. The preparatory factors are slope, lithology, soil depth, land use, etcwhile the triggering factors are heavy rainfall or earthquake.

Indonesia has complex circumstances concerned to landslide threat. It exists in the meetingpoint of three plate tectonics which dynamically move. It is also located in tropical region with 6months of rainy season and various physical characteristics such as: slope, soil, relief, and land use. Thecombination of those conditions makes some parts of Indonesia prone to landslide. The statistical dataasserts that about 11% of the total disaster events in 2008 were landslide. The events set off 73casualties and 1,599 affected people (BNPB, 2008).

One of landslide prone areas is Karanganyar Regency. Landslides occurred in several subdistricts, for instance Ngargoyoso, Tawangmangu, Jenawi, etc. The most damaging landslide took placein Tawangmangu Sub District on December 26th, 2007. This event caused 34 casualties. The drivingfactors of the event were slope of more than 40 degree, amount of rainfall 240 mm per day (Hadmoko etal, 2008), moderate level of potential land movement (PVMBG, 2007) and land use function conversionfrom forest into agriculture (Hadmoko et al, 2008).

Conversion of land use function reveals due to limited land to be used for agricultural purpose.Local community tends to exploit steep slope area as agricultural land (Hadmoko et al, 2008). Land usechanges from tight crop to seasonal plant (strawberry, vegetable, cassava, etc.) in upper slope of LawuVolcano (PVMBG, 2007). The conversion of land use function can be also associated with poorimplementation of existing land use function division by local government and less comprehensive landuse function decision procedure.

Legal Document of Ministry of Agriculture number 837/Kpts/UM/11/1980 (Anonymous, 1980)and number 683/Kpts/UM/8/1981 (Anonymous, 1981) emphasizes that land use function in spatialplanning is generated by means of land capability analysis with scoring method. The analysis considersslope, soil type, and daily rainfall intensity as inhibiting factors. This analysis only deliberates erosionhazard associated with soil type. The landslide susceptibility as a prominent hazard is not explicitlyintegrated.

The issue of integrating landslide susceptibility and land capability for determining land usefunction becomes one of essential parts in spatial planning. Land use function is a basis to propose moresuitable land use planning. Land use function plays an important rule to recognize the appropriate landuse practice. Thereby, the study of determining land capability by involving the landslide susceptibilityinformation turns into the important concern to manage the land in Tawangmangu Sub District. It is alsounknown whether incorporating landslide susceptibility into land capability assessment will result indifferent land use function division.

1.2. Problem StatementTawangmangu Sub District is located in south western flank of Lawu Volcano with slope up to

more than 65%. This area consists of volcanic breccia and tuff with andecite and basalt fragment. Thearea is also covered by loam and clay texture, slow-very fast permeability, and easy to collapse.Furthermore, this area has moderate level of potential land movement. It means that land movement


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often occurs and there is a re-occurrence possibility of the previous land movement, particularlyinitiated by heavy rainfall (PVMBG, 2007).

Act number 26, 2007 organizes the spatial planning in Indonesia (Anonymous, 2007). Section6.1a accentuates that spatial planning in Indonesia has to be conducted by considering physicalcondition of Indonesia which is prone to disaster. It means that the spatial planning of TawangmanguSub District shall implicate landslide information since this area is prone to landslide. Moreover, section5.2d asserts that land use function in spatial planning consists of protected area and cultivated area.Protected areas encompass preserved areas and natural disaster prone areas. Cultivated areas areintended for productive forest, settlement, industry, etc. Thus, spatial planning of Tawangmangu SubDistrict also has to establish appropriate land use function division which includes landslide prone areaas a part of protected areas.

Land use function is one of substansial points in spatial planning process. It is employed as afoundation for further land use plan in spatial planning. Hence, land use function shall be derived fromthorough analysis by contemplating sustainable concept. The inclusive analysis must involve potencyand limitation of the land. This analysis is known as land capability assessment.

Present land use function in study area is developed through land capability analysis. It is basedon Legal Document of Ministry of Agriculture number 837/Kpts/UM/11/1980 (Anonymous, 1980) andnumber 683/Kpts/UM/8/1981 (Anonymous, 1981). Three factors (slope, soil type, and daily rainfallintensity) are combined. Nevertheless, this analysis is not clearly enough in assessing the landcapability. Moreover, the present method only describes erosion hazard related to soil type while thestudy area is also suffered by landslide hazard.

The improved method of land capability analysis is necessary for the future spatial planning.The idea in assimilating landslide susceptibility into more comprehensive land capability assessmentbecomes important. However, it is not known yet how to combine these. Therefore, this study tries toexamine a way to integrate them.

1.3. ObjectivesGeneral objective of this research is to integrate landslide susceptibility information into land

capability assessment in spatial planning. The general objective is detailed into four specific objectives,as follow:a. To generate landslide susceptibility map.b. To propose an integrated method of land capability classification and landslide susceptibility.c. To determine land use function based on the proposed method.d. To evaluate land use deviation by considering the proposed land use function.

1.4. Research QuestionsResearch questions (Table 1.1) are arranged according to four specific objectives as previously

declared.

Table 1.1. Research Questions Associated with Specific ObjectivesNo Specific Objective Research Question

1 To generate landslide susceptibilitymap

a. What kind of parameters used to generate landslidesusceptibility map?

b. How is spatial distribution of landslide susceptibilityzone (very high, high, moderate, low, and very low)?

c. How is the distribution of settlement area regarding toestablished landslide susceptibility map?

2 To propose an integrated method ofland capability classification andlandslide susceptibility

a. Which system of land capability classification is used todevelop the present land use function at localgovernment?

b. What is proposed method for developing land capabilityclassification in this area?

c. Which land characteristics shall be involved in proposedland capability classification?

3 To determine land use functionbased on the proposed method

a. How different are present land use function map andproposed land use function map?


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Figure 1.1. Thesis Structure

Introduction

Literature Review

Study Area and Research Method

Development of Landslide Susceptibility

Land Use Function Division

Identification of Land Use Deviation

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Land Capability Assessment

Chapter 7

Conclusion and Recommendation Chapter 8

4 To evaluate land use deviation byconsidering the proposed land usefunction.

a. How is the present distribution of land use in proposedland use function?

b. Is there any land use deviation? and where is it?

1.5. Thesis Structure

The thesis is organized in a series of chapter (Figure 1.1). Chapter 1 explains the background,objectives, and research questions derived from the specific objectives. Chapter 2 discusses literaturereview concerned with this research. Study area and research method are explained in Chapter 3.Chapter 4 confers development of landslide susceptibility information. The integration landslidesusceptibility information in land capability classification is described in Chapter 5. The result of thischapter is harnessed to generate land use function (Chapter 6) and land use deviation (Chapter 7). Theconclusion and recommendation is presented in Chapter 8.

1.6. Significance of the ResearchLandslide susceptibility is one of the crucial information in spatial planning for landslide prone

area. It gives a description about spatial probability of landslide. The spatial distribution of susceptiblearea acts as vital information in arranging proper land use function. The appropriate land use functionitself is determined through land capability analysis. Therefore, the combination between landslidesusceptibility in land capability assessment is needed to propose suitable land use function.

This research offers a new integrated method which combines landslide susceptibility in landcapability appraisal for dividing land use function. The result can be applied by local government toarrange a better land use function division and further land use plan in spatial planning. The result canbe also applied to declare a strict regulation for a certain area due to landslide threat. For scientist part,this research conveys knowledge in how to integrate landslide susceptibility in land capabilityassessment.

1.7. Scope and LimitationThe scope of the research comprises integration landslide susceptibility information into land

capability assessment to improve present land capability appraisal in spatial planning process. Theintegration result is used to develop land use function and to identify land use deviation. On the otherhand, the constraints in this research are related to data availability and limited time. The limited timeparticularly influences the primary data collection for the whole area. Inaccessibility situation is themain limitation to obtain more comprehensive soil data and landslide location.


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CHAPTER IILITERATURE REVIEW

This chapter consists of several theories related to the research topic i.e. natural hazard, landslide,landslide susceptibility, spatial planning and hazard, spatial planning in Indonesia, land capability onspatial planning in Indonesia, and USDA land capability classification.

2.1. Natural HazardSmith (2001) describes hazard as a general source of danger. Hazard is a naturally occurring or

human-induced process or event with the potential to reveal loss. Hazard is able to create unpredictablelosses and damages to be real. This condition is called disaster. The losses and damages can be sufferedby people, property, and environment.

Hazard can be divided into natural hazard, human-induced and man-made hazard. The term ofnatural hazard is related to natural phenomena without human intervention. The kind of natural hazardsconsists of geologic, hydrologic, atmospheric, and biologic (Table 2.1).

Table 2.1. Some Potentially Hazardous Environmental Elements or EventsNo Kind of

HazardsElements

1 Geologic Mass movement (landslides, avalanches, mudflows), earthquake (groundshaking/tsunamis), volcanic eruption (pyroclastic flows, ash falls), rapidsediment movement (severe erosion/siltation).

2 Hydrologic Flood (freshwater from rivers/lakes/dam bursts), coastal flood (from marinestorm surge/sea level rise), wave action (coastal and lakeshore erosion),drought (from rainfall deficit), rapid glacier advance (surges).

3 Atmospheric Single element (excess rainfall, freezing rain/glaze, hail, heavy snowfalls, highwind speeds, extreme temperatures), combined elements (hurricanes, glazestorms, thunderstorms, blizzards, tornadoes, heat/cold stress).

4 Biologic Severe epidemic in humans (Ebola fever, AIDS, malaria), severe epidemic inplants, severe epidemics in wild animals, animal and plant invasions (locusts,grasshoppers, weeds), forest and grassland fires.

Source: Modified after Hewitt and Burton (1971) in Smith (2001)

2.2. LandslideHighland and Bobrowsky (2008) defines landslide as “a down slope movement of rock or soil,

or both, occurring on the surface of rupture—either curved (rotational slide) or planar (translationalslide) rupture—in which much of the material often moves as a coherent or semi coherent mass withlittle internal deformation”.

Landslide can be distinguished based on its type of movement. The types are fall, topple, slide,spread, flow, and complex (Highland and Bobrowsky, 2008). Each type can be divided into three typesof material, i.e. bedrock, predominant coarse, and predominant fine (Table 2.2). The scheme of eachlandslide type is illustrated in Figure 2.1. The characteristic of each landslide type is described below:a. Fall

The initial process of fall is detachment of soil or rock or both and also from a steep slope alonga surface on which little or no shear displacement has occurred. Thereafter, the material goes downmainly by falling, bouncing, or rolling.

b. ToppleA topple is defined as the forward rotation out of a slope of a mass of soil or rock around a

point or axis below the center of gravity of the displaced mass. Topples can be complex andcomposite and the material consist of rock, debris (coarse material), or earth materials (fine-grainedmaterial). Topple is not only forced by gravity exerted by the weight of material upslope from thedisplaced mass but also it is caused by water or ice in cracks in the mass.

c. SlideA slide can be described as a down slope movement of a soil or rock mass which occurs on

surfaces of rupture or on relatively thin zones of intense shear strain. Movement does not initially


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Figure 2.1. Landslide Types (USGS, 2004)

occur simultaneously over the whole of what eventually becomes the surface of rupture. Thevolume of displacing material enlarges from an area of local failure.

Table 2.2. Classification of LandslidesType of Movement Type of Material

Bedrock Engineering Soils

Predominantly Coarse Predominantly Fine

Falls Rock fall Debris fall Earth fall

Topples Rock topple Debris topple Earth topple

Slidesa. Rotational (few units)b.Translational

Rock slumpRock block slideRock slide

Debris slumpDebris block slideDebris slide

Earth slumpEarth block slideEarth slide

Lateral spreads Rock spread Debris spread Earth spread

Flows Rock flow (deep creep) Debris flow (soil creep) Earth flow

Complex Combination of two or more principal types of movementSource: After Varnes (1978) in Smith (2001)

d. SpreadA spread is an extension of a cohesive soil or rock

mass. It is merged with the general subsidence of thefractured mass of cohesive material into softerunderlying material. Spreads may result fromliquefaction or flow (and extrusion) of the softerunderlying material. Several types of spreads are blockspreads, liquefaction spreads, and lateral spreads.

e. FlowA flow is a spatially continuous movement. The

surfaces of shear are short-lived, closely spaced, andusually not preserved. The component velocities in thedisplacing mass of a flow resemble those in a viscousliquid. There is often a gradation of change from slidesto flows. This situation depends on the water content,mobility, and evolution of the movement.

2.3. Landslide SusceptibilityLandslide susceptibility is defined as “a quantitative or qualitative assessment of the

classification, volume (or area), and spatial distribution of landslides which exist or potentially mayoccur in an area. Susceptibility may also include a description of the velocity and intensity of theexisting or potential landsliding. Although it is expected that landsliding will occur more frequently inthe most susceptible areas, in the susceptibility analysis, time frame is explicitly not taken into account”(Fell et al, 2008).

The susceptibility of landslide in a certain area can be estimated by combining several factors.Those factors are grouped into two categories i.e. environmental factors and triggering factors (VanWesten et al, 2008). Each category can be specified into several data layer, as follow:a. The environmental factors are DEM, slope angle/aspect, internal relief, flow accumulation,

lithology, structure, faults, soil types, soil depth, slope hydrology, main geomorphology units,detailed geomorphology units, land use types, and land use changes.

b. The triggering factors are rainfall, temperature/evapo-transpiration, earthquake, and groundacceleration.

The distribution of landslide susceptible area can be assessed by harnessing several methods.Those are inventory method, statistical method, heuristic method, and deterministic method (Soetersand van Westen, 1996). Each method has own characteristic in relation with the required data and dataprocessing.


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a. Inventory methodInventory method is a preliminary approach to most study of landslide. This method compiles

landslide occurrences in a certain area. It becomes a basis of most susceptibility mapping. Theinformation of landslide occurrences is collected from historical data or aerial photo interpretationsupported by field checking.

b. Statistical methodStatistical method utilizes the combination of several related factors to landslide occurrence in

the past. The factors are calculated statistically. The purpose is to establish quantitative predictionfor the area which is currently free of landslide but the similar conditions still exist.

Statistical method consists of bivariate and multivariate analysis. Bivariate statistical analysiscombines each factor map with landslide distribution map. The weighted values are calculatedbased on landslide density in each parameter class. Multivariate statistical analysis is generated byusing multiple regression analysis and discriminant analysis. This analysis requires continuous data.

c. Heuristic methodHeuristic method can be employed to analyze landslide susceptibility triggered by different

mechanisms, complexity of geological condition, and the small number of actual landslides (Ruffand Czurda, 2007). The expert opinion is needed to assess the landslide potential from preparatoryvariables. The assumption is that the relationships between landslide susceptibility and thepreparatory variables are recognized.

One problem in heuristic method is long term data requirement. It is related to actual landslidesand the causal factors for the same location or for the similar location with comparable geo-environmental situation. This method also has limitation concerned with the subjectivity of weightand rank of the variables.

d. Deterministic MethodDeterministic method is based on slope instability analysis. It can be divided based on the

triggering factor of slope instability, i.e. rainfall and earthquake. The model of rainfall-induced failures combine shallow subsurface flow (pore pressure spatial

distribution) initiated by rainfalls of various return periods. Moreover, predicted soil thicknessand landsliding of the soil mantle are also taken into account.

The model of earthquake-induced failures uses a conventional seismic hazard analysis todetermine Peak Ground Accelerations (PGA) for different return periods. Furthermore, slopestability when subjected to an earthquake with various return periods is observed by utilizing apseudostatic analysis.

Deterministic method is carried out with prerequisite conditions. This method is usually used topredict landslide susceptibility in a small area. The area must have fairly uniform of groundcondition. The landslide type is easy to recognize as well. The method permits quantitative factorsof safety to be calculated by considering the variability of soil properties if necessary. On the othersides, deterministic method has several problems. The problems are high degree of simplification,unaffordable data requirement, and impossibility to obtain the data to use the model effectively.

2.4. Spatial Planning and HazardSpatial planning is a term to define optimal land utilization in a certain area. The land is

managed by taking into account sustainable concept. Land use activities are arranged without disturbingthe environmental balance. The disturbance itself is associated with the probability of hazard. Thereby,spatial planning has several important roles in relation with hazard (Fleischhauer et al, 2005), as follow:a. Keeping a certain area free of development

Development activity in a certain area will attract a lot of people and supporting activities.Mass concentration and many essential activities (trade, business, etc.) put developing area as riskzone as if a particular hazard destructs this area. Thus, development activity must be located inhazard free area. Hazard prone area ought to be kept in natural condition.


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b. Differentiating decisions on land useHazard prone area is a distinctive situation. It shall be contemplated in distinguishing land use

practice. The hazard prone area must be classified as protected area. This region is not allowed to beused for extensive land use practice, such as development of settlement area. Hazard prone areas arebetter to be allocated as natural preserve rather than agricultural land.

c. Recommending legally binding land-use or zoning plans.Hazard information is an important consideration in dividing land allocation. This information

supports the zoning process of land use. The zoning process is organized based on legal regulation.Hence, the established land allocation must be obediently applied in the field. There are also somepunishments for people who break the rule.

d. Reducing hazard potencyThe involvement of hazard information is necessary to recognize an appropriate land use. This

is intended to alleviate the negative impact of hazard. Some cases illustrate that the hazard becomesa disaster due to improper land use application. For that reason, land use practice must envisage theprobability of hazard as a way to minimize the effect.

2.5. Spatial Planning in IndonesiaSpatial planning system in Indonesia is based on Act number 26, 2007 (Anonymous, 2007).

This regulation states that the spatial planning system is developed regarding to administrativeboundaries. There are four hierarchies of spatial planning, as follow:a. RTRW (Rencana Tata Ruang Wilayah / Regional Spatial Plan) Nasional (National Spatial Plan)b. RTRW Pulau (Island Spatial Plan)c. RTRW Provinsi (Provincial Spatial Plan)d. RTRW Kabupaten/Kota (Regency/City Spatial Plan)e. RUTRK (Rencana Umum Tata Ruang Kota)Kecamatan (General Spatial Plan of Sub District City)f. RDTRK (Rencana Detail Tata Ruang Kota)Kecamatan (Detailed Spatial Plan of Sub District City)

The spatial plan of higher administrative level has a function as guidance for the lower one. NationalSpatial Plan guides the development of Island Spatial Plan. The Island Spatial Plan is a reference forgenerating Provincial Spatial Plan, and so on.

Two sections in this act are concerned with hazard and land use function. Section 6.1aemphasizes the necessity to incriminate hazard information in all spatial planning levels. The hazardinformation is implicated in zoning division. The instrument of zoning division consists of specific andstrict spatial rules on each region with certain function. Section 5.2d states that zoning division consistsof protected and cultivated area. Protected areas encompass preserved areas and natural disaster proneareas. Cultivated areas are intended for productive forest, settlement, industry, etc.

This act also conducts punishment mechanism on any actions against the rules of spatialplanning. The sanction is not only given to the permit holder, but also the people who hold theauthorization to release the permit for exploitation. The punishment is intended to give positive effectparticularly in performing law enforcement and reducing possible losses and damages due toinappropriateness implementation of spatial plan.

The process of spatial planning arrangement in Indonesia consists of nine analyses. Allanalyzes refer to Legal Document of Ministry of Settlement and Regional Infrastructure number327/Kpts/M/2002 about Procedures of Province Spatial Planning Arrangement (Anonymous, 2002).Each analysis is carried out for a certain purpose in order to get inclusive result. Those analyzes areexplained below:a. Strategy analysis of development policy

The analysis is intended to explore the aims and goals of development. It is performed toexamine national spatial plan in order to determine how well the role of the lower administrativelevel (province, regency/city) supports the pattern and structure of national space.

b. Regional analysisThis analysis discusses the relationship between province and other areas in terms of social,

economic, environment and culture.


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c. Economic and prominent sector analysisThe aim of this analysis is to reveal sustained regional economic in relation with local

economic within a broader administrative level (national and international). The expected result isthe understandings of economical characteristic at province level.

d. Human resource analysisHuman resource analysis is performed to define human intervention related to social and

economic development. Social factor that influences regional development is also identified.

e. Man-made resource analysisMan-made resource analysis is conducted to identify infrastructure condition, possible problem

that occurs in the development process. This analysis consists of transportation facility analysis,drainage facility analysis, etc.

f. Natural resource analysisThis analysis is executed to obtain the information about environmental condition. The analysis

discusses the development trend in utilizing natural resource and potency which can be improved.The analysis encompasses several sections. Those are land resource, water resource, air resource,forest, and other resources. Land resource section is used to identify the potency of land related toits capability and the recommendation of land use function division (cultivated and protected area).

g. Settlement system analysisSettlement system analysis is generated to recognize condition, number, type, location, size and

interdependency. The result of this analysis is depicted in hierarchy system and function ofsettlement area.

h. Land use analysisLand use analysis is intended to find out land utilization and land suitability for protected and

cultivated area. This analysis describes the trend of activity in a certain area, for instance in theterms of intensity, changes, occupation, and conflict among regions.

i. Institutional analysisThis analysis describes the capacity of government in conducting development process. The

capacity is concerned with organizational structure, human resource, regulation, etc.

The implementation of spatial plan usually meets one crucial problem. The established spatialplan cannot be fully implemented due to land ownership. Land ownership in Indonesia is legalized onUndang-Undang Pokok Agraria (UUPA) number 5/1960 (Kartono et al, 1989). This act declares thatproperty right of land allows the owner to utilize the lands and to take some benefits from them. On theother hand, spatial plan, particularly in province/regency/city is legalized on Peraturan Daerah (Perda).Act Republic of Indonesia number 10, 2004 section 7 states that hierarchy and type of act and regulationconsists of five levels (Anonymous, 2004), as follow:1. Undang-Undang Dasar Negara Republik Indonesia Tahun 1945 (1945 Constitution)2. Undang-Undang/Peraturan Pemerintah Pengganti Undang-Undang (Laws/Governmental

Regulation in Lieu of law)3. Peraturan Pemerintah (Governmental Regulation)4. Peraturan Presiden (Presidential Regulation)5. Peraturan Daerah (Regional Regulation)

Based on the hierarchies, Perda has lower position than Undang-Undang. It means that the force of lawof Perda is weaker than Undang-Undang. Thereby, spatial plan cannot be completely enforced becausecommunity with legal property right has strong legitimacy to exploit the land as they want.

2.6. Land Capability on Spatial Planning in IndonesiaLand capability assessment on spatial planning document in Indonesia is based on Legal

Document of Ministry of Agriculture number 837/Kpts/UM/11/1980 (Anonymous, 1980) and number683/Kpts/UM/8/1981 (Anonymous, 1981). This approach uses scoring method. Three main factors


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(slope, soil type, and average daily rainfall intensity) are employed to divide a certain area into threeland use functions. Those functions are protected area, buffer area, and cultivated area. The cultivatedarea is subsequently specified into yearly cultivated area, seasonal cultivated area, and settlement area.The classification of used factors is shown in Table 2.3 – Table 2.5).

Table 2.3. Slope Classification

Table 2.4. Soil Type Classification

Table 2.5. Average Daily Rainfall Intensity Classification

The classification of land use function is determined based on the accumulative score. The areawith score of ≥ 175 is classified as protected area. The area with score of 125-174 and the score lessthan 125 are categorized as buffer area and cultivated area respectively. Some physical characteristicsare also used to define the land use function, as follow:a. Protected area

Protected area is the area with score of ≥ 175 or has one or several following characteristics: Slope is more than 40% Soil type is regosol, lithosol, organosol, and renzina. Those types are very sensitive to erosion. The area is riverbank. The distance is 100 meter for main river and 50 meter for stream. The area is used to protect water source. The distance from the water source is 200 meter. The area is utilized to protect lake/dam. The distance from the lake/dam is 50-100 meter. The elevation is more than 2,000 meter above mean sea level. The area had been allocated as national park by government. The area is established as protected area due to a specific purpose.

b. Buffer areaBuffer area is located between protected area and cultivated area so that it can have two

functions i.e., as protected area or cultivated area. Buffer area is the area with score of 125-174and/or meets a demand of the following general criteria: Physical condition of the land can be harnessed as economic cultivated area. The location is economically developed as buffer area The land gives benefit for the environment/ecology.

No Class Slope Score

1 Flat 0 – 8% 20

2 Slightly slope 8 – 15% 40

3 Moderately steep 15 – 25% 60

4 Steep 25 – 45% 80

5 Very steep > 45% 100

No Soil Type Score

1 Aluvial,Glei, Planosol,Hidromerf, Laterik ground water (not sensitive with erosion) 15

2 Latosol (less sensitive with erosion) 30

3 Brown forest soil, non calcic brown mediteran (moderately sensitive with erosion) 45

4 Andosol, Laterit, Grumusol, Podsol, Podsolic (sensitive with erosion) 60

5 Regosol, Lithosol, Organosol, Renzina (very sensitive with erosion) 75

No Class Average Daily Rainfall Intensity (mm/day) Score

1 Very low 0 – 13.6 10

2 Low 13.6 – 20.7 20

3 Moderate 20.7 – 27.7 30

4 High 27.7 – 34.8 40

5 Very high > 34.8 50


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c. Cultivated areaThe area with accumulative score of less than 125 is classified as cultivated region. This region

consists of the three land use functions, i.e. yearly cultivated area, seasonal cultivated area, andsettlement area. Yearly cultivated area is the area with score less than 125 and slope of 15-40%. This area has

general characteristic as buffer area. Seasonal cultivated area has score of less than 125. This area is usually employed as seasonal

agricultural purpose. Settlement area has score of less than 125. The slope for settlement area shall be relatively flat,

i.e. 0 - 8%.

Land use function is one of preliminary analyzes in spatial planning. Land use functionrepresents the capability of the land. It is established to support land use planning. On the other words,land use function is a global description which is then elaborated into several appropriate land usepractices. Thereby, land use function division shall be properly implemented.

The enforcement of land use function division faces one significant problem as explained inprevious sub chapter. Land ownership becomes the major constraint in implementing land use functiondivision and land use planning. In addition, there is no boundary which separates each land usefunction. This situation probably drives extensive exploitation in improper location.

2.7. United States Department of Agriculture (USDA) Land Capability ClassificationLand capability classification is one of the interpretive soil groupings. Those are developed

primarily for agricultural purpose, especially farm planning. Land capability classification refers to thepotentialities and limitations of soil –what it is capable of. Land capability classifies a certain area basedon the degree of limitations. It is intended to establish the suitable land use practice.

The USDA land capability classification establishes three main categories of soil groupings,from most general to most specific. These are capability class, capability subclass, and capability unit(Klingebiel and Montgomery, 1966). Capability class is the general category of land capabilityclassification. It consists of eight classes, class I – VIII. Capability subclass is a grouping of capabilityunits which has similar kinds of limitations and hazards. Those limitations and hazards are erosionhazard (e), wetness/excess water (w), rooting zone limitations (s), and climate limitation (c). The naturalhazards recognized are erosion and flooding. Capability unit is a grouping of soils which has the sameresponses to systems of management of common cultivated crops and pasture plants. In one capabilityunit, soils are adapted to the same kinds of common cultivated and pasture plants. Also, they requiresimilar alternatives of management for these crops.

USDA land capability classification requires ten parameters for classifying a certain area into aparticular land capability class. The parameters are slope, erodibility, actual erosion, soil depth, soiltexture, soil permeability, soil drainage, rock fragment, flood threat, and salinity. Those parameters aredescribed below:a. Slope

Slope is the main topographic feature. It greatly influences the capability of land for intensivepurpose. Various land uses can be performed in flat zone while very steep slope area shall not beallowed for extensive utilization due to the risk in disrupting environmental balance. Slope inUSDA classification is divided into seven classes as summarized in Table 2.6.

Table 2.6. USDA Slope ClassificationCode Class Slope

A Flat 0 – 3%

B Undulating 3 – 8%

C Moderately sloping 8 – 15%

D Hilly 15 – 30%

E Moderately steep 30 – 45%

F Steep 45 – 65%

G Very steep >65%


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b. ErodibilityErodibility is defined as the soil sensitivity to erosion. One of the methods to calculate

erodibility index is proposed by Wischmeier et al (1971, in Asdak, 2007), as below:

Where:K = erodibility indexM = (% very fine sand + % silt) x (100-% clay)a = % organic materialb = code of soil structurec = code of soil permeability class

Soil structure is categorized into four classes based on the diameter size (Table 2.7). Soilpermeability is divided into six classes (Table 2.8). The erodibility index itself is grouped into sixclasses as seen in Table 2.9.

Table 2.7. Soil Structure Classification

Table 2.8. Soil Permeability Classification

Table 2.9. Erodibility Index Classification

c. Actual ErosionActual erosion is estimated by observing the present situation of soil layer. This parameter is

grouped into six classes as shown in Table 2.10.

Code Soil Structure Class / Diameter

1 Very fine granular (<1 mm)

2 Fine granular (1 – 2 mm)

3 Moderate and coarse granular (2 – 10 mm)

4 Blocky, plat, massif

Code Class Permeability (cm/hour)

1 Very slow <0.5

2 Slow 0.5 – 2.0

3 Low to moderate 2.0 – 6.3

4 Moderate 6.3 – 12.7

5 Moderate to fast 12.7 – 25.4

6 Fast >25.4

Code Class Erodibility Index

KE1 Very low 0.00 – 0.10

KE2 Low 0.11 – 0.20

KE3 Moderate 0.21 – 0.32

KE4 Moderately high 0.33 – 0.43

KE5 High 0.44 – 0.55

KE6 Very high 0.56 – 0.64

100K = 2,713 M1,14 (10-4)(12-a)+3,25(b-2)+2,5(c-3)


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Figure 2.2. Soil Texture Chart(USDA, 1993)

Table 2.10. Actual Erosion Classification

d. Soil DepthEffective soil depth is the depth of soil which is good for the growth of root. Soil depth is

measured until rock layer which cannot be penetrated by root. The categorization of soil depth isdepicted in Table 2.11.

Table 2.11. Soil Depth ClassificationCode Class Soil Depth (cm)

k0 Deep More than 90 cm

k1 Moderate 50 – 90 cm

k2 Shallow 25 – 50 cm

k3 Very shallow < 25 cm

e. Soil TextureSoil texture is one of important soil characteristics. It influences soil capacity for retaining the

water. This parameter also affects soil permeability and other physical and chemical characteristics.Soil texture is categorized into five classes based on the degree of roughness (see Table 2.12). Theinterpretation of soil texture can be conducted by using the given diagram (Figure 2.2).

Table 2.12. Soil Texture Classification

f. Soil PermeabilitySoil permeability represents the soil ability to flow the

water in saturated condition. The permeability is divided intofive classes as figured in Table 2.13.

Table 2.13. Soil Permeability Classification

Code Class Erosion Characteristic

e0 No erosion -

e1 Minor erosion Less than 25% of topsoil is lost

e2 Moderate erosion 25 - 75 % of topsoil is lost

e3 Moderately severe erosion More than 75 %of topsoil and less than 25% of subsoil arelost

e4 Severe erosion More than 25% of subsoil is lost

e5 Very severe erosion Gully erosion

Code Class Soil Texture

t1 Fine-textured Sandy clay, silty clay, clay

t2 Moderately fine-textured

Clay loam, sandy clayloam, silty clay loam

t3 Medium-textured Loam, silty loam, silt

t4 Moderately coarse-textured

Fine sandy loam, very finesandy loam, sandy loam

t5 Coarse-textured Sands, loamy sands

Code Class Soil Permeability (cm/hour)

p1 Slow < 0.50

p2 Moderately slow 0.5 – 2.0

p3 Moderate 2.0 – 6.25

p4 Moderately fast 6.25 – 12.5

p5 Fast > 12.5


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Figure 2.3. Chart for Estimating Proportions ofCoarse Fragments and Mottles (FAO, 2006)

g. Soil DrainageSoil drainage is related to soil characteristic to restrain the water. It is associated with air

circulation in the soil. Soil drainage condition can be identified from the soil color. The appearanceof yellow, brown, or grey spots in the soil indicates poor soil drainage condition (see Table 2.14).

Table 2.14. Soil Drainage Classification

h. Rock FragmentRock fragment refers to coarse materials both in the soil and on the surface. These materials

affect the growth of plant. The detailed classification of rock fragment in the soil and rock fragmenton the surface is presented below: Rock fragment in the soil

Rock fragment in the soil is observed in upper soil layer (20 cm from the surface). Thematerials are classified as gravel and small rock. Gravel has diameter of 1.2 – 7.5 cm forcircular shape and diameter of 1.2 – 15 cm for flat shape. Small rock has diameter of 7.5 – 25cm for circular shape and diameter of 15 – 40 cm for flat shape. The classification of rockfragment in the soil is displayed in Table 2.15. The existence of rock fragment in the soil can beestimated by using estimation chart as shown in Figure 2.3.

Table 2.15. Classification of Rock Fragment in theSoil

Rock fragment on the surfaceRock fragment on the surface is divided into twogroups. These are stone and rock. Stone freely existsin the surface. It has diameter of more than 25 cm forcircular shape and diameter of more than 40 cm forflat shape. On the other side, rock appears on the surface. It is a part of rock sunk in the soil.The classification of stone and rock on the surface is presented in Table 2.16 and Table 2.17respectively.

Table 2.16. Classification of Stone on the Surface

Code Class Soil Drainage

d0 Excessively drained Water is removed very rapidly.

d1 Well drained Soil has a good air circulation. All soil profile (150 cm) hassimilar color and there are no yellow, brown, or grey spots.

d2 Moderately well drained Soil has a good air circulation in the root zone. There are noyellow, brown, or grey spots up to 60 cm from soil surface.

d3 Somewhat poorly drained Upper layer has a good circulation. There are no yellow, brown,or grey spots up to 40 cm from soil surface.

d4 Poorly drained There are yellow, brown, or grey spots in the upper layer (nearsoil surface).

d5 Very poorly drained All soil layers have yellow, brown, or grey spots.

Code Class Rock Fragment in the Soil

b0 No 0 - 15% of soil volume

b1 Moderate 15 – 50% of soil volume

b2 Much 50 – 90% of soil volume

b3 Very much > 90% of soil volume

Code Class Stone on the Surface

b0 No Stones or boulders cover from 0.01 to 0.1% of the surface

b1 Few Stones or boulders cover from 0.1 to 3% of the surface

b2 Moderate Stones or boulders cover from 3 to 15% of the surface

b3 Much Stones or boulders cover from 15 to 90% of the surface

b4 Very Much Stones or boulders covers more than 90% of the surface


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Table 2.17. Classification of Rock on the Surface

i. Flood ThreatFlood threat classification is based on the actual flood events in a given area. The flood

duration is a key to categorize flood threat (see Table 2.18).

Table 2.18. Classification of Flood Threat

j. SalinitySalinity is a particular parameter in land capability classification. This parameter is usually

harnessed for the dry season area or coastal area. Salinity is stated as dissolved salt contents orelectricity obstruction of soil. Four classes are developed for this parameter as seen Table 2.19.

Table 2.19. Classification of Salinity

All parameters are eventually involved in land capability classification table. Land capabilityclassification is a ranked system based on the severity of land limitations. Thus, the table describes thedistribution of limitations in every land capability class. The limitation becomes greater from class I toVIII (Table 2. 20).

Land capability class is a starting point to determine the appropriate land use practice. Theintensity of land use practice depends on the degree of limitation. The worse limitation causes the lowerthe intensity of land use practice. The severe inhibiting factor obstructs extensive land utilization inrelation with sustainable purpose (Table 2.21).

Code Class Rock on the Surface

b0 No Rocks cover less than 2% of the surface

b1 Few Rocks cover from 2 to 10% of the surface

b2 Moderate Rocks cover from 10 to 50 percent of the surface

b3 Much Rocks cover from 50 to 90 percent of the surface

b4 Very Much Rocks covers more than 90 percent of the surface

Code Flood Duration

O0 In a year, the area is never inundated by flood with duration more than 24 hours

O1 Less than one month, the area is not regularly inundated by flood with duration more than 24hours

O2 In a month per year, the area is regularly inundated by flood with duration more than 24 hours

O3 In 2 – 5 months per year, the area is regularly inundated by flood with duration more than 24hours

O4 In more than six months per year, the area is regularly inundated by flood with duration morethan 24 hours

Code Class Salinity Condition

g0 Free 0 – 0.15% dissolved salt; 0 – 4 (ECx103) mmhos per cm ontemperature of 250C

g1 Slightly influenced 0.15 – 0.35% dissolved salt; 4 – 8 (ECx103) mmhos per cm ontemperature of 250C

g2 Moderately influenced 0.35 – 0.65% dissolved salt; 8 – 15 (ECx103) mmhos per cm ontemperature of 250C

g3 Greatly influenced >0.65% dissolved salt; >15 (ECx103) mmhos per cm ontemperature of 250C


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Table 2.20. Land Capability ClassificationNo Factor Land Capability Classes

I II III IV V VI VII VIII

1 Slope A B C D A E F G

2 Erodibility KE1,KE2

KE3 KE4,KE5

KE6 * * * *

3 Actualerosion

e0 e1 e2 e3 ** e4 e5 *

4 Soil depth k0 k1 k2 k2 * k3 * *

5 Soil texture t1/t2/t3 t1/t2/t3 t1/t2/t3/t4

t1/t2/t3/t4 * t1/t2/t3/t4 t1/t2/t3/t4 t5

6 Soilpermeability

p2/p3 p2/p3 p2/p3/p4 p2/p3/p4 p1 * * p5

7 Soildrainage

d1 d2 d3 d4 d5 ** ** d0

8 Rockfragment

b0 b0 b1 b2 b3 * * b4

9 Flood threat O0 O1 O2 O3 O4 ** ** *

10 Salinity*** g0 g1 g2 g3 ** g3 * **It doesn’t have particular characteristic, ** Inapplicable***it is usually applied in dry season area

Table 2.21. Land Capability Class DescriptionClass Description

I Soils with few limitations

II Soils with some limitations that reduce the choice of plants or require moderate conservationpractices.

III Soils with severe limitations that reduce the choice of plants or require special conservationpractices or both.

IV Soils with very severe limitations that restrict the choice of plants or require very carefulmanagement, or both.

V Soils with little or no erosion hazard but have other limitations impractical to remove that limittheir use largely to pasture, range, woodland or wildlife food and cover.

VI Soils with severe limitations that make them unsuited to cultivation and limit their use largely topasture or range, woodland or wildlife food and cover.

VII Soils with very severe limitations that make them unsuited to cultivation and that restrict their uselargely to grazing, woodland or wildlife.

VIII Soils and landforms with limitations that preclude their use for commercial plants production andrestrict their use to recreation, wildlife, or water supply or to esthetic purposes.

Source: Klingebiel and Montgomery (1966)


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CHAPTER IIISTUDY AREA AND RESEARCH METHOD

Chapter three explains characteristic of study area and method of the research. The characteristics ofstudy area comprise geographical location, geomorphological and geological condition, land use,rainfall intensity, soil, and demographic condition. The research method is divided into three parts, i.e.data preparation/data collection, data processing, and data analysis.

3.1. Study AreaTawangmangu Sub District is located in Karanganyar Regency, Central Java Province,

Indonesia (Figure 3.1 – 3.2). The width area is 7,003 Ha. This sub district is administratively dividedinto ten villages. Those are Tengklik, Gondosuli, Plumbon, Bandardawung, Sepanjang, Karanglo,Nglebak, Tawangmangu, Kalisoro, and Blumbang. This area also consists of 42 sub-villages (dusun), 86dukuh, 99 RW (Rukun Warga), and 344 RT (Rukun Tetangga) (BPS, 2008).

3.1.1. Geographical LocationTawangmangu Sub District is situated between 513319 – 521443 mE and 9151905 – 9156896

mN (Figure 3.3). It has administrative boarders with Ngargoyoso Sub District in the North, Jatiyoso SubDistrict in the South, Karangpandan and Matesih Sub District in the West, and East Java Province in theEast.

3.1.2. Geomorphological ConditionsPhysical condition of Tawangmangu Sub District is geomorphologically influenced by volcanic

activity from Lawu Volcano, Mount Sidoramping, and Mount Jobolarangan. The materials from thosevolcanoes form various environmental features. These features are mainly in terms of lithology andslope. The study area consists of eight geological units. Most of them are composed by andesitic lava,volcanic tuff, breccia, basalt, etc. The area is also characterized by various slopes. Steep (45 – 65%) andvery steep (more than 65%) slope is the dominant situation in study area. (Table 3.1).

Table 3.1. Width Area of Each Slope Class

Source: Data Analysis (2009)

Code Class Slope Width Area(Ha)

Code Class Slope WidthArea (Ha)

A Flat 0 – 3% 11 E Moderately steep 30 – 45% 1,170

B Undulating 3 – 8% 336 F Steep 45 - 65% 1,585

C Moderatelysloping

8 – 15% 638 G Very steep > 65% 1,756

D Hilly 15 – 30% 1,507 Total 7,003

Figure 3.1. SRTM of Java Island

Figure 3.2. Ikonos Image of Tawangmangu Sub District(Google Earth, 2006)


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Figure 3.3. Administration Map of Tawangmangu Sub District

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Geo-Information for Spatial Planning and Risk ManagementGeography Faculty, Gadjah Mada University, Indonesia

International Institute for Geo-Information Scienceand Earth Observation (ITC), The Netherlands Map Created by: Sri Eka Wati (08/276590 /P MU/5638)

PROJECTION:

DATA SOURCE:

UTM Zone 49 S

1. Topographic Map, Poncol and Tawangmangu Sheet,Scale 1:25,000 (2001)

2. Ikonos Image of Google Earth (2006)

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Map 1Administrative of Tawangmangu Sub District

River

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Road Class

Collector

Other

Footpath

Local

Sub-district Boundary

Province Boundary

Village Boundary

Ngargoyoso Sub-DistrictKarangpandan Sub-District

Matesih Sub-District

Jatiyoso Sub-District

East JavaProvince

WGS 1984DATUM:

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Figure 3.4. Landform Map of Tawangmangu Sub District

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Geo-Information for Spatial Planningand Risk ManagementGeography Faculty, Gadjah Mada University, Indonesia

International Institute for Geo-Information Scienceand Earth Observation (ITC), The Netherlands Map Created by: Sri Eka Wati (08/276590/PMU/5638)

DATA SOURCE:

1. Topographic Map, Poncol and Tawangmangu S heet,Scale 1:25,000 (2001)

2. Geological Map, Ponor ogo Sheet,

Scale 1:100,000 (1997)3. Landsat 7 ETM+ (2006)4. S huttle Radar Topographic Mission (SRTM)

5. Field Survey (2009)

LEGEND:

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Volcanic cone of Lawu Volcano

High Hill in Sidoramping Lava Flow

Lawu Lahar Plain

Moderate Hill in Sidoramping Lava Flow

Low hill in Volcanic Rock Formation

Andecite Hill

Limestone Hill

Undulating Terrain in Lava Flow

River Valley

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Front Slope of Lawu Volcano

Lower Slope of Mount Sidoramping

Small Valley in Sidoramping Lava

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Contour Line

Map 2Landform of Tawangmangu Sub District

Province Boundary


Seasonal River

River




East JavaProvince

Landform Boundary

DATUM: WGS 1984

UTM Zone 49 SPROJECTION:Land form map was generated bycombining DEM SRTM with

Landsat ETM 7+ image in order to create

the 3d view (anaglyph). Landformdelineation was also supported by

geological map (li thology) and topographic

map (contour). Study area wasdivided into 13 landfor ms. Land form map

was used asa bas is for determining

the number and the location of soil samp le.

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The topographic and geological condition is the consideration in determining the landforms instudy area. Landform is harnessed as a land mapping unit in this research. The landform is technicallyobtained from visual interpretation of 3D view of Landsat Image, contour, and geological formation. Asa result, study area is classified into 13 landforms (Figure 3.4), as follow:a. Volcanic cone of Lawu Volcano

Volcanic cone area is concatenation of four zones. Those are summit/cone, upper slope, middleslope, and lower slope. The four zones are assumed as one landform due to low accessibility toreach them. The characteristic of each zone is described below: Cone of Lawu Volcano

The summit area of Lawu Volcano is the highest place in Tawangmangu Sub District. Thehighest elevation is 3,262.5 amsl. This area is dominated by the slope of more than 65%. Tuff,breccia, and andesitic lava are the parent materials in this zone.

Upper slope of Lawu VolcanoMost sections of this landform have slope of more than 65%. The area is geologically

formed by Lawu volcanic rock (tuff, breccia, and inserted andesitic lava) combined withandesitic lava from geological unit of Condrodimuko lava. The area is mostly used as forestalthough some areas are abandoned as bare land.

Middle slope of Lawu VolcanoThis landform is laid upon Lawu volcanic rock (tuff, breccia, and inserted andesitic lava)

and Condrodimuko lava (andesitic lava). Slope in this area is slightly sloping compared withthe upper slope. Nevertheless, there are some areas with slope of 45 – 65% and > 65%,particularly in the stream valley. The major land use is forest. Vegetable garden also exists forplanting some vegetable and fruit which needs cold temperature to grow, e.g. carrot andstrawberry.

Lower slope of Lawu VolcanoThis region is a part of Lawu volcanic rock formation. The lithology consists of tuff,

breccia, and inserted andesitic lava. The area is characterized as hilly and moderately steepslope (15 – 45%). The intensity of steep and very steep slope is getting lower than middle slopezone. Forest spreads out in this area possessed by PERHUTANI.

b. Lower slope of Mount SidorampingThis landform is situated in hilly and moderately steep area. It exists upon Jobolarangan breccia

and Condrodimuko lava. The land is broadly utilized by community as vegetable garden. Kinds offruit and vegetable are carrot and strawberry. Forest is also kept to reduce erosion process inmoderately steep area.

c. Undulating terrain in lava flowThe undulating terrain is located in the middle part of Tawangmangu Sub District. It exists

between two landforms, i.e. high hill in Sidoramping lava flow and low hill in volcanic rockformation. This area is geologically set up on Lawu volcanic rock. Most of land is utilized assettlement area and vegetable garden, particularly in the part of region with slope less than 30%. Onthe other side, areas with slope more than 30% are harnessed as pine plantation.

d. High hill in Sidoramping lava flowThis area is influenced by volcanic activity from Mount Sidoramping. The lava flows toward

this area. This landform is dominated by slope more than 65%. The very steep slope hindersintensive land utilization. The land is covered by forest although some barren areas are still found.

e. Moderate hill in Sidoramping lava flowThis area is laid within the path of Sidoramping lava flow. The intensity of steep slope is

smaller than high hill area. Some parts of this zone are used as settlement area even though thetopographic condition represents unsuitable area to be inhabited. Other areas are employed asvegetable garden and mixed garden.

f. Low hill in volcanic rock formationThe lithology of low hill area comprises with tuff, breccia, and inserted andesitic lava. This

area has various slopes from 3% to more than 65%. Hilly areas (15 – 30%) are commonly used as


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settlement area whereas the others are exploited as mixed garden and mixed paddy field withvegetable garden.

g. Small valley in Sidoramping LavaThree small valleys exist in Sidoramping lava formation. Those areas are typified as bowl

shape. It is a lower area surrounded by higher area. Small valley regions are harnessed as settlementarea, vegetable garden, and paddy field. One of those areas is located in Ngledoksari Sub-Village,Tawangmangu Village. This area is known as the location of landslide event occurred on December26th, 2007.

h. River valleyStudy area has two steep river valleys. A river valley is situated in middle part of

Tawangmangu Sub District. This area is steeper the other valley. It is geologically laid uponvolcanic rock formation. The other river valley is positioned in western part. It is situated in Lawulahar formation. The land uses in those two river valleys are mixed paddy field with vegetablegarden and shrub and bush.

i. Eroded volcanic coneEroded volcanic cone is a part of Mount Purung area. It is spatially located between low hill in

volcanic rock and volcanic cone of Lawu Volcano. This area is composed by volcanic tuff, breccia,and inserted andesitic lava. Almost all areas are steep with slope of more than 45%. The land isonly used as forest.

j. Front slope of Lawu VolcanoThis landform confines two landforms, i.e. undulating terrain in lava flow and Lawu lahar

plain. This landform geologically acts a meeting point between Lawu volcanic rock and Lawu laharformation. This area is mostly characterized by undulating and hilly area (8 – 30%). The undulatingslope areas are intensively harnessed as settlement area.

k. Lawu lahar plainLawu lahar plain areas are formed by andecite, basalt, and minor pumice. The land is relatively

flat so that it is commonly exploited as mixed paddy field with vegetable garden. Settlement andpaddy field areas are also spread out in this region.

l. Andecite hillAndecite hill is situated on intrusion rock formation. The area is typified by slope less than

30%. The general land uses in this hill are settlement area, paddy field and mixed paddy field withvegetable garden.

m. Limestone hillThis is a unique landform in study area. Isolated hill composed by limestone exists within

andecite material from Lawu Volcano and Mount Sidoramping (Figure 3.5). The lower part of thehill is utilized as settlement area and mixed garden. The southern area is used as vegetable garden.The materials from this hill are mined by local people.

3.1.3. Geological ConditionsTawangmangu Sub District comprises with a series of young-quaternary volcanic and old-

quaternary volcanic. This is influenced by the process of volcanic activity in Pleistocene and Holoceneperiod. The process in Pleistocene and Holocene period reveals old Lawu Volcano and young LawuVolcano respectively. Those are separated by fault which exists from the south to the west as shown inFigure 3.6.

Study area consists of eight geological units. Each geological unit has own lithologicalcombination. The lithology characteristics influence several physical aspects in study area, e.g. soildevelopment, slope stability, and land productivity. The spatial distribution of geological formation isdepicted in Figure 3.7. The characteristics of those geological formations are explained below:


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Figure 3.6. Fault from southward to westward (yellowline) which separates Old Lawu Volcano and Young Lawu

Volcano

Figure 3.5. Limestone hill

a. Lawu Lahar (Qlla)Lawu lahar consists of andecite, basalt, and minor pumice. Those elements merge with volcanic

sand. This unit spreads out in volcanic foot slope areas and forms several low hills.

b. Condrodimuko Lava (Qvcl)Condrodimuko Lava formation is composed by andesitic lava. The lava is issued from

Condrodimuko Crater to the southwest. The distribution to northwestward is confined by the faultcrossing the peak of Lawu Volcano. Moreover, the lava flow to southward is hampered byCemorosewu Fault.

c. Lawu Volcanic Rock (Qvl)Lawu volcanic rock mostly encompasses volcanic tuff and breccia inserted by andesitic lava.

Volcanic tuff with 2 meter thickness contains andecite, pumice, quartz, feldspar, and minorpyroxene and amphibole fragments. Volcanic breccia with black-grey color comprises withandecite of 5 – 20 cm in diameter and 5 meter thickness. Grey andesitic lava has an averagethickness of 1 meter.

d. Jobolarangan Lava (Qvjl)This formation contains the materials from Mount Jobolarangan. Mount Jobolarangan is the

highest peak in Old Lawu Formation. The materials from this mount are andesitic lava withandesine, quartz, feldspar, and minor hornblende.

e. Sidoramping Lava (Qvsl)Dark grey andesitic lava is released from Mount Sidoramping, Mount Puncakdalang, Mount

Kukusan, and Mount Ngampiyungan. The lava flows to the westward. The lava consists ofplagioclase, quartz and feldspar in plagioclase microlite and volcanic glass.

f. Jobolarangan Breccia (Qvjb)This formation is formed by local volcanic breccia intercalated by andesitic lava. This area is

mainly distributed in Old Lawu formation with slope of 30 – 50%.

g. Wonosari Formation (Tmwl)This area consists of reef limestone and calcarente inserted by conglomeratic limestone and

marl. The lithology develops several low hills with cone shape. The height of the cone isapproximately 20 meter.

h. Andecite (Tma)This intrusion rocks show particular textures. The textures are porphyritic, sub hedral, and 0.5 –

1 meter in size. This formation contains 45% andesine, 15% orthoclase, 5% quartz, 5% mineralswithin plagioclase microlite, and 30% volcanic glass.


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3.1.4. Land UseLand use in Tawangmangu Sub District is classified into ten classes. Those classes are forest,

pine plantation, paddy field, mixed garden, vegetable garden, mixed paddy field with vegetable garden,settlement area, shrub and bush, limestone area, and sparse vegetation in forest region (Table 3.2 andFigure 3.8). Land use classification refers to Malingreau (1977) although there are some modified landuse classes. The modified classes are adjusted by actual land use in study area. Some land uses in studyarea is presented in Figure 3.9 – 3.13.

The distribution of land use depends on topographic condition. Land in lower part of LawuVolcano is intensively used for agricultural activities and settlement area. The agricultural land andsettlement are not only found in relatively flat area but also in undulating and hilly area. On the otherside, the upper part of Lawu Volcano and steep slope areas are allocated as forest, particularly protectedforest (PERHUTANI, 2006).

Table 3.2. Land Use of Tawangmangu Sub DistrictNo Land Use Width Area (Ha)

1 Forest 3,417

2 Pine plantation 65

3 Paddy field 176

4 Mixed garden 652

5 Mixed paddy field with vegetable garden 749

6 Settlement area 935

7 Shrub and bush 11

8 Limestone area 8

9 Vegetable garden 800

10 Sparse vegetation in forest region 190

Total 7,003Source: Visual Interpretation of Ikonos Image of 2006 (2009), Field Checking (2009)

Figure 3.7. Geological Map of Tawangmangu Sub District

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DATA SOURCE:

1. Geological Map, Ponor ogo Sheet,Scale 1:100,000 (1997)

2. Topographic Map, Poncol and Tawangmangu S heet,

Scale 1:25,000 (2001)

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Map 3Geology of Tawangmangu Sub District

AndeciteCandradimuka LavaJobolarangan BrecciaJobolarangan LavaLawu LaharLawu Volcanic RockSidoramping LavaWonosari Formation

Tma

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Qvjb

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Qvl

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Province BoundarySub-district Boundary

Seasonal RiverRiver

Geological Formation




East JavaProvince

DATUM: WGS 1984

UTM Zone 49 SPROJECTION:

Geological map of Tawangmangu Sub-District was derivedfrom geological m ap of Ponorogo sheet. The map wasaddedwith some inform ation from topographic map (river network

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Agricultural activities in study area are dominated by vegetable garden. Some vegetablegardens are mixed with paddy field. The existence of vegetable garden is dispersed in flat up to steeparea. Vegetable garden in steep area is performed by terracing technique. The main products ofvegetable garden are carrot, Chinese cabbage, sweet potato, strawberry, onion, garlic, broccoli, andcauliflower.

Settlement is the most rapid developed land use in study area. This situation is forced by theincreasing of population growth. The growth of settlement area occurs along the road and in distantarea. Settlement in remote area has been supported by utility service, particularly electricity. Many localroads are also built to connect the settlement in remote area to center of the city.

Figure 3.12

Figure 3.11

Figure 3.13

Figure 3.9. Vegetable Garden in Hilly AreaFigure 3.10. Settlement in Undulating Terrain AreaFigure 3.11. Pine Trees in Front Slope of Lawu Volcano AreaFigure 3.12. Mixed Garden at Moderate Hill in Sidoramping LavaFigure 3.13. Paddy Field at Low Hill in Volcanic Rock Formation

Figure 3.10

Figure 3.9

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Map 4Land Use of Tawangmangu Sub District

Local

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Forest

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Vegetable Garden

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Sparse Vegetationin Forest RegionVegetable Garden

Village Boundary

Province Boundary





East JavaProvince

DATUM: WGS1984


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Figure 3.8. Land Use Map of Tawangmangu Sub District


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3.1.5. Rainfall IntensityRainfall intensity in Tawangmangu Sub District is measured from two rainfall gauges. The

gauges are located in Blumbang (Blumbang Village) and Somokado (Tawangmangu Village). Therainfall gauge in Blumbang Village is no longer used since 1993. Thus, the continued measurement isonly done in Somokado gauge.

Average monthly rainfall intensity for study area is calculated by using daily rainfall data from1986 to 2008. For Blumbang gauge, the calculation of average monthly rainfall intensity is done byusing data from 1986 to 1992. The result shows that average monthly rainfall intensity in Somokadogauge is higher than Blumbang gauge. Average monthly rainfall intensity for other gauges surroundedstudy area (Matesih, Jatiyoso, Karangpandan, and Gayamdompo) is also lower than Somokado gauge.Average monthly rainfall intensity for study area and surroundings is shown in Table 3.3 and Figure3.14.

Table 3.3. Monthly Rainfall Intensity of Tawangmangu Sub District and SurroundingsRainfallGauge

Monthly Rainfall Intensity (mm)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg

Somokado 576 561 457 318 141 81 45 65 60 178 319 480 273

Blumbang 570 536 365 238 130 99 84 54 52 84 231 373 235

Matesih 438 467 396 286 108 92 52 38 30 186 326 398 235

Jatiyoso 427 417 377 240 115 77 30 97 52 170 311 354 222

Karangpandan 429 434 406 276 140 101 66 39 40 197 291 387 234

Gayamdompo 371 371 306 248 126 105 58 29 41 145 254 367 202Source: Public Work Department of Karanganyar Regency (1986-2008)

3.1.6. Soil CharacteristicsThe observation of soil properties is done as the major requirement in assessing land capability

in study area. The explored soil characteristics primarily comprise depth, texture, permeability, soildrainage, and rock fragment. The depth, drainage, and rock fragment are observed in the field. Textureand permeability are analyzed in soil laboratory.

Field observation and laboratory analysis convey several results. Field observation shows thatstudy area mostly has soil depth more than 90 cm. Some particular areas have very shallow soil, forinstance limestone hill. Moreover, almost of study area is relatively well drained even though somelocations are poorly drained due to the influence of topographic situation. Soil layers in most locationsalso have rock fragment percentage less than 15%. On the other hand, laboratory analysis states that thetexture in study area pervades clay, clay loam, loam, and sandy loam. In addition, the permeability isclassified as slow, moderately slow, moderately fast, and fast.

3.1.7. Demographic ConditionsTawangmangu Sub District is inhabited by 44,892 people (BPS, 2008). The highest populated

area is in Tawangmangu Village (8,440 people) whereas the lowest populated area is in GondosuliVillage (3,435 people). In the terms of population density, Tawangmangu Village is the highest densearea (2,504 people/km2) whilst Gondosuli Village is the lowest dense area (178 people/km2) (Table 3.4).

Figure 3.14. Monthly Rainfall Intensity Chart (Data Analysis, 2009)


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Table 3.4. Population Data of Tawangmangu Sub DistrictNo Village Width

Area(km2)

The Number ofPopulation (people)

The Number ofFamily

PopulationDensity

(people/km2)

1 Bandardawung 3.01 3,993 1,147 1,327

2 Sepanjang 5.65 3,787 931 670

3 Tawangmangu 3.37 8,440 2,271 2,504

4 Kalisoro 10.58 4,437 1,145 419

5 Blumbang 11.12 3,986 909 358

6 Gondosuli 19.25 3,435 951 178

7 Tengklik 8.10 3,801 1,067 469

8 Nglebak 2.34 5,189 1,391 2,218

9 Karanglo 1.86 3,578 961 1,924

10 Plumbon 4.75 4,246 1,125 894

Total 70.03 44,892 11,898 641Source: BPS (2008)

3.2. MethodThe research was split into three stages. The stages were data preparation/data collection, data

processing, and data analysis. Data preparation/data collection and data processing were conductedbefore and after field work. Data analysis was done after field work. The sequence step of the researchis shown in Figure 3.15.

Data preparation/data collection was accomplished to provide required data. Secondary datawas achieved by institutional survey. Several institutions were visited to gather the information needed.The primary data were compiled in field work session.

Data processing was performed to manage the obtained data. Some secondary data wereprocessed before the field work. The processed data were tentative result that had to be verified in thefield. Apart from that, the other data were processed after the field work. The data particularly need tobe analyzed in laboratory (soil properties). Data processing was performed by means of GeographicInformation System (GIS) and Remote Sensing application.

Data analysis was intended to achieve the answer of each research question. The analysis wasdone by using the result from data processing stage. The detailed explanation of research method isdescribed below:

3.2.1. Data Preparation/Data CollectionThe research required primary and secondary data. Primary data were associated with soil

properties and landslide events. Those data were obtained from field work and laboratory analysis. Thesecondary data were gathered from some related institutions. The compulsory data are described inTable 3.5. The documentation of several data collection activities is presented in Appendix 4.a. Secondary data collection

Main secondary data for this research were geological map, topographic map, rainfall intensity,landslide events, and satellite imageries. Other required data which were also collected wereerodibility index, soil type, population data and spatial planning document. The obtained spatialplanning documents consisted of Regional Spatial Plan (RTRW) of Karanganyar Regency 1997 -2006, Detailed Spatial Plan of Subdistrict City (RDTRK) of Tawangmangu 2007 - 20161, andGeneral Spatial Plan of Subdistrict City (RUTRK) of Tawangmangu 1990/1991 – 2009/2010.

Secondary data collection was also executed through interview session. The interview wasconducted with Development and Planning Board (BAPPEDA) of Karanganyar Regency. It wasintended to evaluate present land capability classification developed by local government. Based onthe result of interview, proposed land capability classification was established by involvinglandslide susceptibility information.

1Mid Report of Detailed Spatial Plan of Subdistrict City of Tawangmangu 2007-2016


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Figure 3.15. Research flowchart

LiteratureReview

TopographicMap

Soil Map Spatial Planning(RTRW)

GeologicalMap

MethodologyArrangement

DataCollection

SatelliteImageries/SRTM

Matching

Field Work

Pre-Field Work

Field Work

Post-Field Work

Evaluate PresentLCC

LandslideEvents

Lithology Administrative

Boundaries Road

Contour

Slope

Landsat Ikonos

VisualInterpretation

SRTM

Anaglyph

Interpretation

Landform Map Tentative LandUse Map

TentativeLandslide Map

ProposedLand

CapabilityClassification

Slope Soil Depth Soil Texture SoilPermeability

FinalLandslideEvent Map

Actualerosion

Soil

Drainage

Rock

Fragment

Weighted-Score

Landslide Susceptibility

Land Capability Class

Land Use Function

Classification

Overlay

Land Use Deviation

Conclusion and Recommendation

FinalLand

Use Map

Data

Process

Result

Flow chart for determining land susceptibility

Flow chart for classifying land capability

ErodibilityIndex

Soil Type

River Network

Drainage

Density

BareLand/SparseVegeta

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Table 3.5. Data RequirementNo Data Information Source

1 Geological map Lithology PUSLITBANG GEOLOGI (GeologicalResearch and Development Center), scale1:100,000

2 Topographic map Administrativeboundaries

Contour Road network River network

BAKOSURTANAL (National CoordinatingAgency for Surveys and Mapping), scale1:25,000

3 Rainfall Daily rainfall intensity Public Work Department of KaranganyarRegency

4 Landslide Landslide occurrence Dinas KESBANGLINMAS of KaranganyarRegency

The office of Tawangmangu Sub District Village offices in Tawangmangu Sub

District Field checking

5 Satelliteimageries

Land use (distributionof settlement area)

Road network Landform

Ikonos image (Google Earth , 2006) Landsat ETM, 2001 SRTM (Shuttle Radar Topographic

Mission) Field checking

6 Soil properties Soil type Soil depth Soil texture Soil permeability

PUSLITANAK, scale 1:250,000 Field checking Laboratory analysis

7 Erodibility Erodibility Previous research and literature study

8 Actual erosion Actual erosion Field checking and literature study

9 Soil drainage Soil drainage Field checking

10 Rock fragment Rock fragment Field checking

11 Spatial planningdocument(RTRW,RUTRK,RDTRK)

Method in determining landcapability for land usefunction

BAPPEDA (Development and Planning Board)of Karanganyar Regency)

12 Statistical data Population (total, density) BPS (Center of Statistical Bureau) ofKaranganyar Regency

b. Primary data collectionPrimary data were acquired from field survey. Two surveys were performed, i.e. soil survey

and landslide inventory survey. Soil survey was done to compile the information of soil properties.The information was concerned with depth, texture, permeability, actual erosion, soil drainage, androck fragment. On the other side, landslide inventory survey was organized to collect the spatialdistribution of landslide location.

Soil survey was accomplished for taking 35 soil samples. The number of soil samples for eachlandform was based on the width area of every landform. The number of samples was obtained bydividing the width area with 4 cm2 of output scale map. The output scale map is 1:60,000. It meansthat the width area of each landform should be divided by 144 in order to obtain the number ofsamples in every landform. Nevertheless, the accessibility was also considered to get the soilsample. Thus, the number of samples for two landforms (volcanic cone of Lawu volcano and highhill in Sidoramping lava) was less than ideal situation due to low accessibility in those areas (Table3.6 and Figure 3.16).


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Table 3.6. The Number of Samples for Each LandformNo Landform Width Area (Ha) The Number of Samples

1 Volcanic cone of Lawu Volcano* 2,134 6

2 Lower slope of Mount Sidoramping 140 1

3 Undulating terrain in lava flow 245 2

4 High hill in Sidoramping lava flow* 1,439 5

5 Moderate hill in Sidoramping lava flow 908 6

6 Low hill in volcanic rock formation 766 5

7 Small valley in Sidoramping lava 160 1

8 River Valley 113 1

9 Eroded Volcanic cone 97 1

10 Front slope of Lawu Volcano 121 1

11 Lawu lahar plain 652 4

12 Andecite hill 116 1

13 Limestone hill 112 1

Total 7,003.0 35Source: Data Analysis (2009), * not the whole area is accessible

Soil survey was conducted through particular method. Detailed methods in soil survey were: Soil depth was measured by using bore. The depth was calculated from the surface to rock layer

by considering the assumption that more than 90 cm is classified as deep. Soil texture was observed by taking approximately 1 kg soil sample in horizon A. The samples

were analyzed in soil laboratory in order to achieve the percentage of very fine sand, sand, silt,and clay.

Soil permeability was taken by ring permeability. The samples were also sent to laboratory tobe analyzed.

Figure 3.16. Soil Sample Distribution Map of Each Landform in Tawangmangu Sub District

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2. Geological Map, Ponorogo Sheet,

Scale 1:100,000 (1997)3. Landsat 7 ETM+ (2006)4. Shuttle Radar Topographic Mission (SRTM)


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Map 5Soil Sample Distribution of Each Landform

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DATUM: WGS1984

UTM Zone 49 SPROJECTION:Soil sample map was developedbyplotting the location of soi l sample.

The number of soi l was based on

the width area of each landform.The number of samples was obtained

by dividing width area with 4 cm2 of output

scale map. The outputscale map was 1:60,000. It means thatthe width area of each landform should

be divided by 144 in order to obtainthe number of samples. Nevertheless,the accessibil ity was also considered

for taking soil sample.

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Actual erosion was formerly observed in soil sample point. This observation is not sufficient toestimate the actual erosion in scope of landform. Thereby, this parameter was determined byusing three variables, i.e. drainage density, distribution of sparse vegetation/bare land, and soiltype.

Soil drainage condition was recognized based on the appearance of yellow, brown, or greyspots in the soil.

Rock fragment was evaluated regarding to the existence coarse material in the soil, and rock orstone in the surface. Coarse material in the soil was estimated by harnessing rock fragmentchart as shown in Figure 2.3.

The information of landslide events was collected from sub district office, village offices andlocal community. The landslide data collection by visual interpretation could not be fully done dueto the lack of data, especially satellite imageries. The interpretation only harnessed Ikonos image(2006) from Google Earth. Therefore, the data of landslide event was improved by visiting thereachable locations of landslides. The coordinate of the location was taken by using GPS. The resultof landslide inventory survey is presented by landslide point map as illustrated in Chapter IV.

3.2.2. Data ProcessingThe first data processing was performed prior to field work. This activity was done to prepare

the preliminary information. This information was checked in the field, i.e. land form map, tentativeland use map, and tentative landslide point map. Each of them was derived from the following method:a. Land form map was generated by combining DEM SRTM with Landsat ETM 7+ image in order to

create the 3d view (anaglyph). Landform delineation was also supported by geological map(lithology) and topographic map (contour line pattern). Developed land form map was used as abasis for determining the number and the location of soil sample. The landform map is illustrated inFigure 3.4.

b. Tentative land use map was created by visual interpretation of Ikonos image (2006) from GoogleEarth. The interpretation result was then checked in the field.

c. The initial landslide information from local government in the level sub district and village wasdeveloped as a landslide point map. The map was checked in the field and subsequently evolved byadding the new location of landslide events that was found during the field work.

The second data processing was conducted after field work. All data were processed to comeup with the expected result. Landslide susceptibility, land capability, and land use function are the mainresult in this research. Every required result was processed through particular method, as below:a. Development of landslide susceptibility map

Landslide susceptibility map was made by using Heuristic approach with weighted overlaymethod. Related variables used were slope, lithology, soil depth, soil texture, soil permeability, andland use. Each variable was classified into four classes and was given a certain score and weightedvalue. The score and weighted value was developed in ILWIS. The score was generated from pairwise method and weighted value was obtained from rank method. Detailed information of landslidesusceptibility is described in Chapter IV.

b. Land capability assessmentLand capability assessment was basically done by using the method from Klingebiel and

Montgomery (1966) and Arsyad (1989). This method was modified by including landslidesusceptibility information (Table 5.2). The proposed land capability classification acted as a basis todetermine land capability of study area. The procedure was by matching the actual situation instudy area with proposed land capability classification.

Land capability was assessed in general and detailed version. Those versions basically usedlandform as a land mapping unit. However, the method of those versions was a little bit different.The method for each version is illustrated in Table 3.7. Apart from that, this research also examinedthe other way in determining land capability by involving landslide susceptibility information. Landcapability was formerly classified without taking into account landslide susceptibility. The obtainedland capability class was subsequently overlaid with landslide susceptibility. All mentionedprocesses of land capability assessment are fully described in Chapter V.


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Table 3.7. The Comparison Method of General and Detailed Versionin Land Capability Assessment

General Version Detailed Version

Assumption:One landform has a quite similar characteristicso that one landform is represented by oneland capability class.

Method: The dominant value for each land

capability’s parameter was determined asa representative value in each landform.

The value was then matched withproposed land capability classification.

Assumption:One landform actually has several different landcapability classes due to spatial distribution of slopeand landside susceptibility.

Method: Land capability was established as in general

version. The general land capability class was overlaid

by slope and landslide susceptibility map The overlay result was then matched with

proposed land capability classification.

c. Establishment of land use functionLand use function was developed by using two methods. The methods were Ministry of

Agriculture’s method (scoring method) and proposed method. Two methods were employed tocompare the result. Scoring method employs three variables, i.e. slope, soil type, and average dailyrainfall intensity. The classification of each variable is shown in Table 2.3 – 2.5. Land use functionis divided based on accumulative score. The score of ≥ 175 is categorized as protected area. Thescore of 125-174 is classified as buffer area and the score of less than 125 is allocated as cultivatedarea. On the other hand, proposed method harnesses land capability class for determining the landuse function. The conversion diagram of land capability class and land use was applied (Table 3.8).Based on the given diagram, class I to IV can be harnessed as cultivated area. Class V to VI shall beapplied as grazing area. Otherwise, class VIII has to keep as nature conservation area. The obviousdiscussion session about land use function is demonstrated in Chapter VI.

Table 3.8. Correlation between Land Capability and Land UseLand

CapabilityClass

Intensity of Land Use

WildLife

Forestry Grazing Cultivation

Limited Moderate Intense Limited Moderate Intense VeryIntense

I

II

III

IV

V

VI

VII

VIISource: Klingebiel and Montgomery (1966)

Land use function division was done through general and detailed version. General versionclassified the land use function according to landform boundary. On the other side, the detailedversion ignored the landform boundary. The difference of general and detailed version in land usefunction division is described in Table 3.9. The clear explanation about land use function ispresented in Chapter VI.


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Table 3.9. The Difference of General and Detailed Version in Land Use Function DivisionMethod General Version Detailed Version

Ministry of Agriculture’smethod (scoring method)

The dominant value for eachland use function’s variable(slope, soil type, and averagedaily rainfall intensity) wasdetermined in each landform.

The value was given a certainscore.

The score was accumulated ineach landform

Three required variables(slope, soil type, andaverage daily rainfallintensity) were directlyoverlaid. Each variable classhas been given a certainscore.

The score was finallysummed.

Proposed method General land use function wasestablished by using the result ofgeneral version of land capabilityassessment.

Detailed land use function wasspecified by employing the resultof detailed version of landcapability assessment.

3.2.3. Data AnalysisThe analysis process included several tasks, as follow:

a. Identification of settlement area distribution in each landslide susceptibility classThe identification process was performed by overlying present settlement area distribution and

landslide susceptibility. It was proposed to recognize the settlement areas which were situated inhigh and very high susceptible area to landslide. The result of this analysis can be used as importantinformation for future land management.

b. Explanation of existing and proposed landslide mitigation strategiesExisting landslide mitigation strategies collected in the field was described in order to find the

inadequacy strategies for the future. Proposed mitigation strategies were then arranged as arecommendation for local government and local community.

c. Comparison land use function division based on Ministry of Agriculture’s method (scoring method)and proposed method

The comparison was accomplished to obtain the differences between two methods. Thedistinctions between them were descriptively asserted. The comparison was also done for generaland detailed version of both methods.

d. Identification of land use deviationLand use deviation refers to inappropriateness condition between land use function and land

use practice. Land use deviation was recognized by comparing land use function map and presentland use map. The identification of land use inexpediency was developed for general and detailedversion. General and detailed land use deviation was developed based on general and detailed landuse function respectively. The identification analysis of land use deviation also included thediscussion about the cause of land use deviation. This analysis stage is obviously expressed inChapter VII.

3.2.4. Equipment and softwareEquipment and software employed during the research were:

a. Equipment: computer, scanner, printer, and field work tools (bore, ring permeability, abney level,hammer, Global Positioning System (GPS), digital camera, printed satellite imageries, printedthematic maps, and soil sample forms)

b. Software: Arcview 3.3, ArcGIS 9.2, ILWIS 3.3, ERDAS Imagine 9.1, and Microsoft Office (Word,Excel, Powerpoint).


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Figure 4.1. Landslide in Ngledoksari Sub-Village

CHAPTER IVLANDSLIDE SUSCEPTIBILITY OF TAWANGMANGU SUB DISTRICT

This chapter implicates detailed explanation related to landslide susceptibility. Actual landslides thathave been inventoried are presented. The method, result, and analysis of landslide susceptibilityconcerned with settlement area distribution are briefly described in this chapter.

4.1. IntroductionLandslide susceptibility is defined as spatial probability of landslide occurrence in a certain

area. Landslide susceptibility represents the prone degree of landslide. The higher landslidesusceptibility level stands for the higher probability of landslide occurrence. The probability of landslidecan be estimated by using several approaches (statistic, deterministic, or heuristic). Those approachesanalyze a complex combination of some physical-environmental aspects, for instance: slope, lithology,soil properties, and rainfall. In this research, landside susceptibility information was generated byharnessing heuristic approach with weighted-score method.

4.2. Landslide Events in Tawangmangu Sub DistrictA big landslide occurred on December 26th, 2007

in Ngledoksari Sub-Village, Tawangmangu Village(Figure 4.1). This event caused 34 victims and 105damaged houses (Local Government of KaranganyarRegency, 2007). This event was the worst landslide inTawangmangu Sub District within the last five years.

Other landslide events often took place in thestudy area. There were 34 landslide locations found duringthe field work (see Table 4.1 and Figure 4.10). Most oflandslides were located in Sepanjang and BandardawungVillage (Figure 4.2). However, the revealed damages andlooses in those two villages were not as big as inTawangmangu Sub District.

Several landslides also occurred in remote area. Four locations of landslides were identifiedthrough visual interpretation of Ikonos image (2006) from Google Earth (Figure 4.3). The landslides aresituated in landform of high hill in Sidoramping lava flow. This area is administratively included inGondosuli Village. This location is associated with very steep slope (more than 65%) and it isabandoned as sparse vegetated area.

Landslide events are mainly situated in agricultural land (mixed garden and vegetable garden)(Figure 4.4 – 4.5). It means that human intervention in harnessing the available land sometimes revealsnegative impact for the environment. One of the crucial conditions is related to development ofvegetable garden in steep slope area. Fertile land with good climate supports the expanded landutilization. The demand in providing agricultural commodities for Tawangmangu Sub District andsurroundings also drives rapid growth of agricultural land in study area.

Figure 4.2. The Number of Landslide Events inEach Village (Data Analysis, 2009)

The Remnant of Landslide

Figure 4.3. The Remnant of Landslide Evidence inIkonos Image (Google Earth, 2006)


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Some landslide events cause damages and disruption in settlement area (Figure 4.6 – 4.9b). Thesettlement areas are generally located in relatively steep area and in flat area surrounded by steep zone.The damages in settlement area encompass damaged houses and roads. Several damaged houses androads in those locations can be still identified while the others are not. Most damaged houses due tolandslide have been repaired. Almost all damaged roads have been also reconstructed.

Some people in study area have own perception about landslide. They consider landslide as athreat for human but they do not have ability for moving to the safer area. The lower salary andmemorable history coerces them to live in the same location. Moreover, they have to adapt to physicalcondition since there is no other alternative areas as living space. Those perceptions are one of thehindering factors in landslide overcoming strategies, particularly related to the effort in relocatingaffected people.

Table 4.1. Landslide Events in Tawangmangu Sub DistrictNo Village The Number of

Landslide EventsDamages and Losses

1 Bandardawung 7 Damaged agricultural land and road

2 Sepanjang 10 12 damaged houses, damaged road, and agricultural land

3 Tawangmangu 1 34 casualties and 105 damaged houses

4 Kalisoro 4 Damaged agricultural land

5 Blumbang 4 Damaged agricultural land

6 Gondosuli 2 Shrub and bush

7 Tegklik 4 35 damaged houses, damaged road and agricultural land

8 Nglebak 1 Damaged road

9 Karanglo 1 Damaged road

10 Plumbon 5 4 damaged houses, damaged road, shrub and bushSource: Sub District and Village Offices in Tawangmangu Sub District; Field Checking (2009)

Figure 4.4 Figure 4.5 Figure 4.6

Figure 4.7

Figure 4.4. Damaged agricultural land (mixed garden) in Bandardawung VillageFigure 4.5. Damaged agricultural land (vegetable garden) in Kalisoro VillageFigure 4.6. Damaged houses and road in Tengklik VillageFigure 4.7. Repaired house because of landslide in Sepanjang VillageFigure 4.8. Direction of landslide and susceptible house in Sepanjang VillageFigure 4.9a. Damaged road due to landslide in Karanglo VillageFigure 4.9b. Direction of landslide and susceptible house in Karanglo Village

Figure 4.8 Figure 4.9a Figure 4.9b


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4.3. Landslide Type in Tawangmangu Sub DistrictLandslide type in study area is mainly rotational

(Figure 4.11). This type has unique characteristic in which thesurface of rupture is curved upward (spoon-shaped). The slidemovement is more or less rotational about an axis that isparallel to the slope contour. This landslide type is triggered byrainfall or earthquake. High rainfall intensity forces theincreasing of water content in the soil up to saturatedcondition. In relation with slope, this circumstance finallyreduces resistant force and enlarges driving force slidingprocess (Highland and Bobrowsky, 2008). Figure 4.12 showsrotational landslide in Bandardawung Village.

Rainfall is the most triggering factor of landslideevents in study area. A big landslide in Tawangmangu Sub Districtwas primarily triggered by high rainfall intensity. The recordeddaily rainfall intensity from five rainfall gauges on December 27th,2007 tended to be the highest during the last 23 years. Totalrainfall intensity in that day was approximately similar even higherthan monthly rainfall intensity. The high rainfall intensity alsocaused other landslide events in the other villages. Hence, theextreme rainfall intensity plays a main role in landslide mechanismin study area.

The materials of landslide event in study area commonlyconsist of soil and rock. Soil is the dominant material. Thedomination of soil material appears as a consequence in terms of deep soil in the study area. On theother hand, landslide with rock material can be particularly identified in limestone hill as seen in Figure4.4.

Figure 4.11 Rotational Landslide Scheme(Highland and Bobrowsky, 2008)

Depletion Zone

Depositional Zone

Figure 4.12. Rotational Landslidein Bandardawung Village

Figure 4.10. Landslide Event Map of Tawangmangu Sub District

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Village Offices (2009)


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Map 6Landslide Events in Tawangmangu Sub District

Contour Line

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4.4. Development of Landslide Susceptibility InformationLandslide susceptibility information was developed by means of heuristic approach with

weighted-score method. The score was obtained from pair wise method whereas weight value wasachieved by applying rank method. Both application methods are available in ILWIS. The susceptibilityinformation was executed by involving six parameters, i.e. slope, lithology, soil depth, soil texture, soilpermeability, and land use. Each class of parameters was given a certain score which was thenmultiplied by a weight value. The score and the weight value depict the percentage of influence inlandslide occurrence.

Landslide susceptibility parameters used in this researchwas generated from several sources. Those are topographic map,geological map, and soil analysis. Some of them, i.e. geologicalmap and soil analysis do not have detail information so that theeffective scale of the assessment is not as precise as in the result.

The parameters of landslide susceptibility are classifiedinto three groups. Those are topographic, material, and dynamic(Figure 4.13). The topographic condition controls the possibility ofmass failure. The materials play two roles, i.e. soil as mass blockand lithology as slip surface. Dynamic group takes a part as anindirect factor that influences slope stability. Each group comprisesparticular parameter (Table 4.2), as follows:a. Topographic group consists of one parameter, i.e. slope. Slope

is the main factor that affects in increasing shear stress and alsoreducing shear strength. The final weight of landslidesusceptibility parameters shows that slope has the highestweight value.

b. Material group is divided into lithology and soil. Lithology isparent material. It plays a role as slip surface. Soil propertiesrefer to depth, texture, and permeability. Soil is mass blockupon parent material. Lithology is given the higher weightbecause well compacted geological formation reduces the soil to collapse.

c. Dynamic group refers to land use. Land use affects the increasing of pressure for soil. The land usepractice done without considering slope situation enlarges the possibility of soil to fall down.

Rainfall is also one of the triggering factors in landslide occurrence. Rain infiltration driveshydrostatic pressure, enlarges water pressure in soil, and induces a change of consistency. This situationreveals a decrease of cohesion and internal angle friction (Sopheap, 2007). On the other words, waterabsorbed by soil adds water pressure in the soil, forces the escalating of soil mass, and finally increasesburden for slope. Since the average monthly rainfall intensity of the study area shows a quite similarcondition, rainfall parameter is neglected.

The six parameters are divided into four classes. Each parameter class is ranked according tothe sensitivity to landslide mechanism. The sensitivity is determined through several assumptions asexplained below:a. Slope

Slope is the main factor in landslide occurrence. It controls driving force (shear stress) andresisting force (shear strength). The higher of the slope is associated with the higher of the shearstress. It means that the probability of failure is getting bigger. Thereby, the higher slope class isgiven the higher score. Slope map of study area is portrayed in Figure 4.14.

b. LithologyRock type represents some particular characteristics. The hard and massive rock are generally

resistant to erosion (Anbalagan and Singh, 2001), e.g. andecite and limestone. Andecite andWonosari formation (limestone) is set up with the lowest score. On other sides, Lawu lahar andJobolarangan breccia are more brittle than lava formation (Jobolarangan lava, Sidoramping lava,Candradimuka lava) due to the high amount of sand fragment. Apart from that, rock composed bysandstone is more vulnerable to erosion so that it is more susceptible to landslide. Lawu volcanicrock is geological formation formed by sandstone material. Geological map has been presented inFigure 3.7.

Where:

F = safety factorc = cohesion (Pa= N/m2).A = length of the block (m).W = weight of the block (kg).β = slope surface inclination (°).φ = angle of shearing resistance (°)

Figure 4.13. Slope Stability Diagram

(ITC, 2009)


Page | 35

c. Soil depthSoil depth influences the shear stress and shear strength. The depth of soil is associated with the

weight of soil. It is assumed that the deeper the soil, the weightier the mass. Thus, the higher scoreis allocated to the deeper soil. Soil depth in study area is spatially depicted in Figure 4.15.

d. Soil textureSoil texture is the weight proportion of the separates for particles less than 2 mm. The texture

can be recognized from a laboratory particle-size distribution (USDA, 1993). The soil with finetexture (clayey soil) has small pores and liberates the water gradually. It means that clayey soil iseasier to be saturated than sandy soil. Hence, clayey soil is more susceptible to landslide becausethis soil can retain more water. This condition causes the increasing the weight of soil mass.Classification of soil texture in Tawangmangu Sub District can be seen in Figure 4.16.

e. Soil permeabilityPermeability can be defined as the velocity of a certain porous material for flowing the water or

other liquids at standard condition (De Boodt, 1971). Soil permeability is related to soil texture. Theclayey soil is more vulnerable to landslide because it has lower permeability than silt and sandysoil. Therefore, the slower the permeability represents the higher the possibility of landslide. Thesoil permeability map is illustrated in Figure 4.17.

f. Land useLand use is an indirect indicator of slope stability (Anbalagan and Singh, 2001). Sparse

vegetation enhances the effect of weathering and erosion. House construction in settlement areaalso enlarges weight to the slope (Smith, 2001). Vegetable garden in steep slope area increases thesusceptibility of landslide as well. Regarding to lithology, limestone area are less prone to landslide.Paddy field is also resistant to erosion and landslide as if it is located in flat area. Presentdistribution of land use is shown in Figure 3.8.

Table 4.2. The Weighted and Score of Landslide Susceptibility ParametersNo Parameter Weighted factor Parameter’s class Score

1 Slope 40.8 Flat and undulating (0 – 8%)Moderately sloping (8 – 15%)Hilly and moderately steep (15 – 45%)Steep (>45%)

0.1030.2130.4491.000

2 Lithology 24.2 Andecite, Wonosari formationJobolarangan lava, Sidoramping lava, Candradimuka lavaLawu lahar , Jobolarangan brecciaLawu volcanic rock

0.0870.2020.4891.000

3 Soil Depth 10.3 Very shallow (<25 cm)Shallow (25 – 50 cm)Moderate (50 – 90 cm)Deep (>90 cm)

0.2000.0000.0001.000

4 Soil Texture 6.1 Sandy loam, loamy sand, and sandLoam, silty loam, and siltSandy clay loam, clay loam, and silty clay loamSandy clay, silty clay, and clay

0.0980.2080.4641.000

5 SoilPermeability

2.8 Moderately fast, fast (> 6.25 cm per hour)Moderate (2.0 – 6.25 cm per hour)Moderately slow (0.5 - 2.0 cm per hour)Slow (<0.5 cm per hour)

0.1030.2380.5021.000

6 Land Use 15.8 Limestone area, paddy field, pine plantationShrub and bush, mixed garden, forestMixed paddy field with vegetable gardenSettlement, vegetable garden, sparse vegetation in forestregion

0.1050.2360.5071.000

Source: Data Analysis, 2009


Page | 36

Figure 4.14. Slope Map of Tawangmangu Sub District

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International Institute for Geo-Information Scienceand Earth Observation (ITC), The Netherlands Map Created by: Sri Ek a Wati (08/276590/P MU/5638)

DATA SOURCE:


2. Data Analysis (2009)

LEGEND:

500 0 500 1000 1500 2000 2500

Meters



Lawu Lahar Plain



Andecite Hill

Limestone Hill


River Valley





mE

mE mE

mE

mN

mN

mN

mN

Map 7Slope of Tawangmangu Sub District

Slope Class

0 - 3% (Flat)

3 - 8% (Undulating)

8 - 15% (Moderately Sloping)

15 - 30% (Hilly)

30 - 45% (Moderately Steep)

45 - 65% (Steep)

>65% (Very Steep)

Seasonal River

River

East JavaProvince





Province Boundary

Landform BoundaryDATUM: WGS1984


Slope map was der ived from contour l ine. The contour wasconverted into raster format. It was then pr ocessedby using slope tool in ArcGIS. Sl ope was classified

based on USDA slope class ification.N

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Figure 4.15. Soil Depth Map of Tawangmangu Sub District

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Lawu Lahar Plain



Andecite Hill

Limestone Hill


River Valley





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Map 8Soil Depth of Tawangmangu Sub District

Soil Depth Class

Deep (>90 cm)

Very Shallow (<25 cm)

East JavaProvince





Province Boundary

Seasonal River

River



Soil depth was measured in the field. The common situationof soil depth in particular landform was used as

a representative soil depth condition for a given landform. N

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Page | 37

Figure 4.16. Soil Texture Map of Tawangmangu Sub District

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DATA SOURCE:



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LEGEND:

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Meters



Lawu Lahar Plain



Andecite Hill

Limestone Hill


River Valley





mE

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Map 9Soil Texture of Tawangmangu Sub District

Soil Texture Class

Clay

Clay Loam

Loam

Sandy Loam

East JavaProvince





Province Boundary

Seasonal River

River

Landform BoundaryDATUM: WGS 1984


Soi l texture info rmation was obtained by analyzing

the soi l sample in soil laboratory. The dominant textureconditon in each landform represented the common

circumstance for every landform. The map was added

some info rmation from toporaphic map,

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Figure 4.17. Soil Permeability Map of Tawangmangu Sub District

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River Valley





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Map 10Soil Permeability of Tawangmangu Sub District

Soil Permeability Class

Fast (>12.5 cm/hour)

Moderately Fast (6.25 - 12.5 cm/hour)

Moderately Slow (0.5 - 2.0 cm/hour)

Slow (<0.5 cm/hour)




East JavaProvince


Province Boundary

Seasonal River

River



Soil per meabil ity sam ple was taken byusing ring permeabili ty.The sample was analyzed in soi l laboratory. The dominant

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the genera l condition for every landfor m. N

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Page | 38

4.5. Landslide Susceptibility ZoneLandslide susceptibility in this research is categorized into five classes. Those classes are very

low, low, moderate, high, and very high. Each susceptibility class is divided based on the range of totalscore. The score range for each class is very low (less than 28), low (28 – 45), moderate (46 – 63), high(64 – 81), and very high (more than 81).

Landslide susceptibility analysis gives several results. Most areas in Tawangmangu Sub Districtare prone to landslide. More than one third of study area (42%) is classified as high and very highsusceptible area. Moderate susceptible zone covers 43% of total area (2,993 Ha). It is only 15% of totalarea (1,041 Ha) that is included as very low and low susceptible (Table 4.3). Spatial distribution oflandslide susceptibility is shown in Figure 4.18. Detailed distribution of each landslide susceptibilityclass in relation with landform is described below:

Table 4.3. The Width Area of Landslide Susceptibility ClassSusceptibility

ClassWidth Area

(Ha)Susceptibility

ClassWidth Area

(Ha)

Very Low 24 High 2,609

Low 1,017 Very High 360

Moderate 2,993 Total 7,003Source: Data Analysis, 2009

The very low susceptible area is situated in middle part of small valley in Sidoramping lavaflow. This zone is utilized as paddy field. The area is typified by moderately sloping (8 – 15%),moderately fast permeability, and loam texture. The existing situations reduce the probability oflandslide event in this area.

Low susceptible area exists in most areas of andecite hill, Lawu lahar plain, small valleys inSidoramping lava flow, and lower slope of Mount Sidoramping. Some areas in northern part oflimestone hill are also included in low susceptible zone. Low susceptible areas are mainly located in theslope of 0 – 30%. The land uses are varied, i.e. settlement area, paddy field, vegetable garden (carrot,garlic, onion, and strawberry), mixed paddy field with vegetable garden, and forest. In addition, thisarea is also characterized by moderately slow up to fast permeability regarding to clay loam and loamtexture.

Moderate susceptible area is scattered in more than one third of Tawangmangu Sub District(43% of total area). It is the dominant landslide susceptible class in study area. The area is largelypositioned in slope of more than 30%. Nevertheless, some areas in Lawu lahar plain are also included asmoderate susceptible even though they have slope of less than 30%. The given condition is affected bythe broadly existence of settlement area and mixed paddy field with vegetable garden. Besides, the soilin this area has low permeability because of clay loam texture.

High susceptible areas are mostly located in low hill in volcanic rock formation, moderate hillin Sidoramping lava flow, front slope of Lawu Volcano, and eroded volcanic cone. Large areas involcanic cone of Lawu Volcano are also categorized in high susceptible region. High susceptible areasgenerally take place in steep area. Those areas are also dispersed in some land uses, i.e. settlement area,mixed garden, and vegetable garden. The intensive development of those land uses and the brittle parentmaterial enhances the probability of landslide in this zone.

The highest susceptible areas are concentrated in northern part of study area. The areas pervadetwo landforms, i.e. river valley and low hill in volcanic rock formation. Both are laid upon breakableparent material, i.e. Lawu volcanic rock. Moreover, very steep slope (more than 65%), the broadexistence of mixed paddy field with vegetable garden, slow up to moderately slow permeability, andclay-clay loam texture bring the accumulation of the most driving factor of landslide in this area.

4.6. Settlement Area in Landslide Susceptibility ZoneThe development of settlement area increases rapidly. It is initiated by population pressure. The

increasing number of population enlarges the demand of living space. The need of living place inTawangmangu Sub District forces local community to harness every possible location for building theirhouses. Statistical data states that the width area of settlement area increases 4.65% within seven years.The width of settlement area in 2003 was 619.2 Ha (BPS, 2003) and it becomes 935 Ha in 2009 (DataAnalysis, 2009). Unfortunately, the development of settlement area sometimes does not take intoaccount the hazard probability.

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Settlement areas in study area are broadly distributed from flat zone to steep zone. Local peoplemostly build their houses in relatively flat areas but those flat areas are sometimes surrounded by steepslope. It is found that many settlements areas are constructed in hill side or below the road (Figure 4.19– 4.21). This circumstance reveals the risk related to landslide threat.

Landslide is one of the prerequisite in determining suitable location for settlement area. USDA(1983, in Hardjowigeno et al, 1994) states well and moderate suitable areas for settlement have to freeof landslide (Table 4.4). The area with landslide experience is not recommended as settlement.Therefore, the identification of existing settlement in landslide susceptible area becomes important tospatially find out the unsuitable development of settlement area. It is also intended to gather thedistribution of settlement area as a location of exposed population to landslide.

Table 4.4. Land Suitability Criteria for Settlement PurposeNo Soil Characteristics Land Suitability

Well Moderate Poor

1 Subsidence depth (cm) - - 30

2 Flood susceptibility Without Without

3 Water table height (cm) > 75 45 - 75 < 45

4 Shrink-swell value (COLE) 0.03 0.03 – 0.09 > 0.09

5 Soil texture according Unified System OL, OH, PT

6 Slope (%) < 8 8 - 15 > 15

7 Soil depth (cm)HardSoft

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> 100> 50

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9 Gravel-pebble contents (>7.5 mm) (% weight) < 25 25 - 50 > 50

10 Landslide - - PresentSource: USDA, 1983 in Hardjowigeno et al, 1994

The identification of settlement area in landslide susceptible zone is obtained by overlayinglandslide susceptibility map and present settlement area distribution. The result explicitly declares thatthere are many settlement areas are situated under landslide threat. More than a half of settlement areas(51%) are located in moderate susceptible area. Moreover, 35% of settlement area (330 Ha) exists inhigh and very high susceptible zone (Table 4.5 and Figure 4.22).

The existence of settlement area in landslide prone area really needs the attention from localgovernment. The number of vulnerable population due to landslide threat must be considered. Localauthority is suggested to array mitigation strategies for reducing the negative impact of landslide. Oneof those strategies is related to land use policy. Land use policy for development of settlement area shallbe focused on landslide risk reduction.

Figure 4.19. Settlement Area inHillside in Bandardawung

Village

Figure 4.20. Settlement Areabelow the Road in Blumbang

Village

Figure 4.21. Settlement Area inHillside in Tawangmangu

Village


Page | 41

Table 4.5. Distribution of Settlement Area in Each Landslide Susceptibility ClassNo Susceptibility

ClassWidthArea(Ha)

Village Sub-Village

1 Very Low - - -

2 Low 129 BandardawungTawangmangu

Gondang, Bandar, Mloko, DawungNglurah, Mogol, Ngledoksari

3 Moderate 476 BandardawungKaranglo

PlumbonNglebakSepanjang

TawangmanguKalisoroBlumbangGondosuli

Pelas, Gamping, Ngasem, SlojokKaranglo, Blimbing, Barakan, Kongan,Sadakan Lor, Sekuwung, Pedan, CepogoCumpleng, Pakem, Watusambang, KarangweruNglebak, Ngudal, Nglegok, GondangMargosanten, Genengan, Tapan, Genengrejo,SendangBamo, Nano, Ngunut, Beji, BanjarsariKalisoro, Kramat, Panjat Kidul, Panjat LorOmbang-ombangGondosuli Lor, Gondosuli Kidul, Bularejo,Tlogodringo

4 High 306 Plumbon

SepanjangBlumbangGondosuliTengklik

Dukuh, Gude, Setugu, Tarakan, Dukun, PampungNgledokBlumbang Kidul, Blumbang LorDawuhan, Tegalrejo, Tawang, Banaran Atas,Ngledok, Banaran BawahDempul, Sendang, Gundolorejo, Ngepeng, Selere,Tengklik, Sodong, Ngemplak, Guyon, Pidar

5 Very High 24 This class is only dispersed at some small areas in Gude (PlumbonVillage), Blumbang Kidul (Blumbang Village), and Tegalrejo(Gondosuli Village).

Total 935Source: Data Analysis, 2009

507000

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915

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DATA SOURCE:

1. Landsl ide Susceptibil ity Map (2009)2. Land Use Map ( 2009)3. Topographic Map, Poncol and Tawangmangu Sheet,

Scale 1:25,000 (2001)

LEGEND:

500 0 500 1000 1500 2000 2500

Meters

GONDOSULI

TENGKLIK

BLUMBANG

SEPANJANG

PLUMBON

TAWANGMANGU

KALISORO

NGLEBAK

BANDARDAWUNG

KARANGLO

mE

mE mE

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Map 12Settlement Area Distribution in Landslide Susceptibility Zone

in Tawangmangu Sub District

Road Class

Collector

Other

Footpath

Local

Seasonal River

River

Province Boundary

Sub-district Boundary Very Low

Very High

Moderate

Low

High

Susceptibility Class

Sett lement Area

Village Boundary

East JavaProvince




DATUM: WGS 1984


The dis tribution of settlement area in each landslidesusceptibil ity class was recognized by overlying presentsettlement area map with landslide susceptibi lty map.

Settlement area map was taken from recent land use map. N

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Figure 4.22. Map of Settlement Distribution in Landslide Susceptibility Zone of Tawangmangu Sub District


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4.7. Existing Landslide Mitigation StrategiesThe number of actual landslide events in Tawangmangu Sub District shows that this area is

relatively prone to landslide. Landslides have revealed disturbance and disruption for community. It isnot only damaged houses but the number of casualties as well. Thereby, it is important to organize somestrategies as a part of prevention action to minimize thelandslide impacts.

Local communities and related parties have conductedsome activities in relation with landslide mitigation strategies,as follow:a. Constructed some warning signs in landslide prone area.

Warning board is found at landslide location in TengklikVillage (Figure 4.23) and at the edge of the road inGondosuli Village.

b. Constructed landslide early warning tool. This tool isconnected to the land. The tool gives warning sign throughloud siren when the land shakes. The tools are positioned inNgledoksari Sub-Village, Tawangmangu Village and inGuyon Sub-Village, Tengklik Village. It is found that twoof three warning tools in Ngledoksari Village are out of order (Figure 4.24). It is recognized fromthe broken string connection.

c. Developed a landslide susceptibility map. This map is adhered in the office of Tengklik Villagebecause the map is only made for Tengklik Village (Figure 4.25). The map was generated bystudent during dedication action period to community (Kuliah Kerja Nyata, Gadjah MadaUniversity, 2009).

d. Built retaining wall. The retaining wall is constructed for strengthening road construction in steeparea. The retaining wall can be found in a new collector road connecting Karanganyar Regency andMagetan Regency (Figure 4.26). Some local roads are also invigorated by combining rock andcement.

e. Disseminated information of landslide. The information consists of landslide hazard overview,evacuation planning, and landslide susceptibility map (Figure 4.27). The information is compiled inlandslide information board. This information only exists in Tengklik Village.

The present landslide mitigation strategies are not sufficient. The existing landslide mitigationstrategies are only locally conducted. It is not adequate regarding to the width of landslide prone area.Thus, the improvement and additional activities shall be performed.

4.8. Proposed Landslide Mitigation StrategiesProposed landslide mitigation strategies are arranged for improving the existing strategies. The

strategies are organized based on common landslide mitigation actions that have been conducted inother regions. Those are divided into two parts, strategies conducted by local government as theauthority whether in regency, sub district, or village level and strategies executed by local community aspossible affected people. The implementation process needs cooperation between community andgovernment in order to create harmonious practice. The proposed mitigation actions for TawangmanguSub District are described below:

Figure 4.24.Landslide EarlyWarning Tool in

NgledoksariVillage

Figure 4.25. LandslideSusceptibility Map of Tengklik

Village

Figure 4.23.Landslide

Warning Sign inTengklik Village

Figure 4.26. Retaining Wall inCollector Road between

Karanganyar Regency andMagetan Regency

Figure 4.27. LandslideInformation Board in Tengkik

Village


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4.8.1. Local Government Strategiesa. Develop detailed landslide susceptibility map

The general multi hazard map is available in KESBANGLINMAS office. It is made inregency scale and involves several hazards, such as flood, landslide, and earthquake. Detailedlandslide susceptibility map is only obtained in Tengklik Village made by UGM. Hence, a newdetailed hazard map shall be established, particularly in scale of sub district. For Tawangmangu SubDistrict, the map must be focused on landslide hazard since this area is more vulnerable tolandslide. Local government can work together with academic institution for the expert assistance.

b. Conduct regular landslide inventorySome landslide data used in this research are achieved from local government offices in

regency, sub district, and village. The available data do not represent all occurred landslide events.Only severe landslide events causing serious destruction and disruption are listed. As aconsequence, the independent landslide inventory survey is performed by researcher in order to getmore comprehensive data.

The landslide event mapping is urgently needed for Tawangmangu Sub District. It is not onlyintended to spatially recognize the distribution of landslide event but also to verify the reliability ofdeveloped landslide susceptibility map. The landslide inventory can be carried out by field checkingor by visual interpretation of satellite imageries.

c. Involve landslide information in spatial planningLandslide susceptibility and hazard zoning are more likely to be applied in initial stage of

development (Fell et al, 2008). The landslide zoning is used as basis information in controlling landallocation in landslide prone area. The land use planning policy can eventually establish restrictionrule related to rapid development in landslide susceptible area. The obtained spatial planningdocuments, RTRW 1997 – 2006 and RDTRK 2007 – 2016, do not bring in hazard information yet.Thereby, the existing spatial planning is suggested to be revised by considering the possible hazard.

d. Construct and maintain landslide early warning systemLandslide early warning system is one of the important tools in landslide mitigation strategies.

Some landslide early warning tools have been constructed in Ngledoksari Sub-Village(Tawangmangu Village) and Guyon Sub-Village (Tengklik Village). Some of them recently are nolonger functioned. In this manner, it is required to form cooperation in maintaining the systemamong local government, local community, and other related parties. In addition, the number of thetools shall be added due to the extensiveness of landslide prone area.

e. Build strengthened structure in landslide prone areaTopographic situation is one important consideration in road and building construction. Road

construction by cutting the slope and road construction in steep area must contemplate the slopestability. The construction shall be supported by an appropriate structure. The retaining walls fromconcrete material must be also constructed for keeping the slope stability. Furthermore, the propergeo-technical application in relation with road and building construction has to be applied.

f. Disseminate landslide susceptibility information to the lower authority and local communityLandslide susceptible information can be harnessed to recognize the distribution of susceptible

zone. It can be also used to array the recommendation in reducing landslide impacts. It means thatdeveloped landslide susceptibility information shall be informed to lower authority and localcommunity. It is proposed to increase the community awareness of landslide probability.

g. Prepare evacuation planningThe evacuation planning consists of the readiness in providing place, route, and supporting

material. The evacuation place is positioned in safer area with good accessibility. This location willbe used when landslide occurs or the possible landslide is predicted to be happened. Route isplanned to facilitate the evacuation session and distribution of social aid. The supporting materialencompasses several items that are needed in disaster location and in refuge, such as food,medicine, cloth, and water.


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4.8.2. Local Community Strategiesa. Recognize natural sign of landslide

Some natural signs can be identified prior to landslide. Cracks in the land surface, prolongedheavy rain, and earthquake are common conditions before landslide event. After recognizing thelandslide precursor, local community shall move in safer area.

b. Avoid extensive land utilization in steep areaSlope is the most important factor in landslide mechanism. The stability of slope can be

disturbed by human intervention. Improper land use practice forces the slope to be unstable. Hence,the appropriate method of land utilization has to be precisely defined. The assistance from theexpert can be involved for guiding local community towards sustainable land use.

c. Participate in maintaining landslide early warning systemDamaged landslide early warning tools can be evaded through community based

participation. Local community is learnt in how to maintain the system. Contact person from relatedinstitutions must be also determined for supporting the maintenance process.

d. Report landslide event to local authorityLack of landslide database can be solved by the involvement of local community. The

community is forced to inform all landslide events which occurs in their area. The landslide event isreported to the nearest local authority (Head of Rukun Tetangga or Rukun Warga). The informationis then compiled in higher authority (dukuh, dusun, village, sub district, and so on).

e. Cultivate several kinds of plants for strengthening the soilSeveral kinds of plants can be utilized to increase soil strength. They usually have upside

down root with many or few branches (Triwibowo, 2001). Those plants are useful for enhancing thepower to retain soil mass movement. The plants are listed in Table 4.6.

Table 4.6. List of Plants for Strengthening the SoilUpside Down Root with Many Branches Upside Down Root with Few Branches

Kemiri (Alerius mollucana) Mahoni with big leaves (Swietania macrophyla)

Laban (Vitexpubercens) Renghas (Gluta reghas)

Dlingsem (Homaium tomentisum) Jati (Tectona grandis)

Mindi (Meliaale darach) Sono Kembang (Plerocoupus oleosa)

Johar (Cassa stanessa) Sonokeling (Dalbegia latifolia)

Acsiavillosa Cassia fistuta

Eucalyptus alba Trengguli (Bauhina hirsolt)

Leucana glauta Tayuman (Tamarindhus indieus)

Paraserienthes falcataria Asam Jawa (Acacia leucophola)

Bungur (Lagerstroemia speciosa) Pilang (Albizzia lebbeck)

Beringin (Banyan) Kesambi (Sehlechard)Source: Triwibowo, 2001


Page | 45

CHAPTER VLAND CAPABILITY ASSESSMENT OF TAWANGMANGU SUB DISTRICT

Chapter five explains the integration of landslide susceptibility information in land capabilityassessment. Land capability analysis is developed in general and detailed version. In addition, thediscussion about the existing land capability classification created by local government is described inthe initial section.

5.1. IntroductionLand capability assessment is a systematic land appraisal. This is a part of land evaluation

process. The concept of land capability is formerly developed for agricultural purpose. It categorizes acertain area based on the potency and inhibiting aspects for sustainable usage (Arsyad, 1989). Thismethod is used to meet the need in recognizing an appropriate land use regarding to actual condition ina certain area. Since spatial planning is also made to properly manage the available land, land capabilitymethod is effective to be applied in spatial planning arrangement.

5.2. Land Capability Assessment Developed by Local GovernmentLocal government of Karanganyar Regency has applied land capability method in arranging

Regional Spatial Plan (RTRW) of Karanganyar Regency 1997-2006 (BAPPEDA, 1997) and DetailedSpatial Plan of Sub District City (RDTRK) of Tawangmangu 2007-2016 (BAPPEDA, 2007). Theinterview session with staff of Development and Planning Board (BAPPEDA) gives a result that landcapability is harnessed to describe the common land characteristic and to determine land use function.

Land capability assessment in RTRW is made to illustrate the general land characteristic. Thegeneral characteristic is then applied for recognizing Exertion Land Region (Wilayah TanahUsaha/WTU). WTU is a policy concept of land use which is adjusted by a particular elevation andnatural condition of Indonesia. WTU is merely focused on the land division based on elevation andslope.

Land capability assessment for recognizing general land characteristic is formulated by usingfive parameters, i.e. slope, soil depth, texture, drainage, and erosion. Every parameter is classified intocertain classes as depicted in Table 5.1. Those parameters are overlaid in order to obtain variouscombinations among them. As a result, general characteristic of land in Karanganyar Regency are:effective soil depth is more than 90 cm; the general soil texture is moderate and fine; the area is neverinundated; and the slope variety is from 0 – 2% to more than 40%. For Tawangmangu Sub District, thegeneral land characteristics are slope 15 – 40% and more than 40%; effective soil depth 60 – 90 cm;moderate texture (loam); never inundated; and no erosion. Land capability assessment performed inRTRW is portrayed in Figure 5.1.

Table 5.1. Classification of Land Capability Parameters in RTRWNo Slope No Soil Depth No Soil

TextureNo Drainage No Erosion

1 0 – 2% 1 >90 cm 1 Moderate(loam)

1 Neverinundated

1 Noerosion

2 2 – 15% 2 60 – 90 cm 2 Fine(clay)

2 Sometimesinundated

2 Eroded

3 15 – 40% 3 30 – 60 cm 3 Coarse(sand)

3 Inundated

4 >40% 4 < 30 cmSource: BAPPEDA (1997)

Land capability analysis is also conducted to establish land use function. The land use functionconsists of protected, buffer, and cultivated area (yearly cultivated, seasonal cultivated, and settlement).The used method refers to Legal Document of Ministry of Agriculture number 837/Kpts/UM/11/1980(Anonymous, 1980) and number 683/Kpts/UM/8/1981 (Anonymous, 1981). This method employs threeparameters, i.e. slope, soil type, and average daily rainfall intensity. Those parameters are classified asshown in Table 2.3 – 2.5. The land capability analysis for land use function division is completelypresented in Chapter VI.


Page | 46

5.3. Proposed Land Capability ClassificationAct number 26, 2007 emphasizes the involvement of hazard information in spatial planning

(Anonymous, 2007). Hazard information is needed to control extensive land use practice, particularly inhazard prone area. Hazard information is also urgently required as a part of mitigation strategies toreduce the hazard impact. Thereby, hazard information is supposed to portray not only the transpiredhazard but also the probability of hazard in the future.

RTRW of Karanganyar Regency 1997-2006 and RDTRK of Tawangmangu 2007-2016 do notclearly include hazard information. It is only erosion that is already considered in land capabilityassessment in RTRW. RDTRK also merely uses soil type as a parameter representing sensitivity toerosion. Thus, the present spatial plan shall be improved because study area is not only suffered byerosion but also by landslide hazard.

Landslide, as a prominent threat in study area, shall be integrated in the spatial planning inorder to meet the prerequisite from Act number 26, 2007. Landslide susceptibility information is neededto organize the existing land for sustainable purpose. The type and intensity of land use practice shall bedistinguished based on the susceptible degree to landslide. It means that landslide susceptibility has tobe mixed with other land characteristics to determine the proper land use in a certain area.

Proper land use can be generated from land capability analysis. This analysis is done by usingseveral physical land traits (topographic, soil, and hazard). The existing land capability assessment, asmentioned before, unfortunately does not use comprehensive land characteristic. Landslide informationis not yet included as well. Therefore, a new proposed method is developed according to USDAapproach.

The proposed method is intended to obtain thorough description of land capability byconsidering landslide hazard. Landslide susceptibility is added as one of inhibiting factors. Theproposed land capability classification omits two factors, i.e. flood threat and salinity. Flood is not theimportant hazard in study area. On the other hand, salinity is not applied because it is only valid for dryseason area. Proposed method also implicates landslide susceptibility in sub class division. Sub classrepresents the worst condition as the most influencing factor in land capability. The sub class refers tothe rule from Klingebiel and Montgomery (1966) and Arsyad (1989). For proposed sub class division,

Figure 5.1. Land Capability Map Developed by Local Government in Regency Scale(BAPPEDA, 1997)

Tawangmangu Sub District


Page | 47

landslide susceptibility is included in sub class “e” together with slope, erodibility, and actual erosion.The sub class classification is mentioned below: Sub class “e” is intended to slope, erodibility, actual erosion, and landslide susceptibility. Sub class “w” is allocated for soil drainage and flood threat. Sub class “s” is for soil depth, texture, permeability, rock fragment, and salinity. Sub class “c” is owed by climate factor (temperature and rainfall).

The proposed land capability classification assumes that the increasing of susceptibility level isin line with the increasing of constraint factor (Table 5.2). Very low landslide susceptibility is set up inclass I and II. The existence of settlement areas prosecutes the lowest landslide probability so that verylow susceptibility of landslide is recommended for those classes. Low susceptibility of landside isallocated for class III and IV. Moderate, high, and very high susceptibility are added in class VI, VII,and VIII respectively. Landslide susceptibility level is not included in class V because this class isassociated as inundation zone.

Table 5.2. Proposed Land Capability ClassificationNo Inhibiting Factor Land Capability Class

I II III IV V VI VII VIII

1 Slope A B C D A E F G

2 Erodibility KE1,KE2

KE3 KE4,KE5

KE6 * * * *

3 Actual erosion e0 e1 e2 e3 ** e4 e5 *

4 Soil depth k0 k1 k2 k2 * k3 * *

5 Soil texture t1/t2/t3 t1/t2/t3

t1/t2/t3/t4 t1/t2/t3/t4 * t1/t2/t3/t4 t1/t2/t3/t4

t5

6 Soil permeability p2/p3 p2/p3 p2/p3/p4 p2/p3/p4 p1 * * p5

7 Soil drainage d1 d2 d3 d4 d5 ** ** d0

8 Rock fragment b0 b0 b1 b2 b3 * * b4

9 Landslidesusceptibility

LS1 LS1 LS2 LS2 ** LS3 LS4 LS5

* It doesn’t have particular characteristics, ** InapplicableSource: Klingebiel and Montgomery (1966), Arsyad (1989), and Modified (2009)

5.4. General Land Capability Class Based on Proposed MethodGeneral land capability assessment is performed based on landform. It is assumed that the area

classified as the similar landform has relatively akin characteristics. Regarding to the number of soilsamples in each landform, the dominant value for each inhibiting factor is established as a commoncircumstance in each landform. The overview of constraint factors is presented below:a. Slope

Slope is one of crucial factors in land capability appraisal. Slope plays a role in restrictingintensive land utilization, particularly in steep slope area. This is concerned with the probability indisturbing slope stability. Slope stability is highly correlated with landslide hazard. Hence, slope isthe most consideration in managing the land for avoiding landslide impact.

Study area is mainly dominated by four slope classes, i.e. hilly, moderately steep, steep, andvery steep (Table 3.1). Those areas mostly exist in northern and southern parts of study area. On theother hand, the middle part of study area is characterized by flat, undulating, and moderatelysloping zone. In relation with landform, the slope in each landform is varied. One landform consistsof numerous slope classes. Therefore, the generalization process was done in order to define typicalslope in each landform.

The generalized slope comprises with four classes, i.e. class C, D, F, and G. Slope of 8 – 15%(class C) exists in landform Lawu lahar plain while class D (15 – 30%) is spread in eight landforms.Slope of more than 45% (class F and G) largely exists in four landforms which are directlyassociated to Lawu Volcano and Mount Sidoramping. Those landforms are volcanic cone of LawuVolcano, eroded volcano cone, high hill and moderate hill in Sidoramping lava flow.


Page | 48

b. ErodibilityErodibility describes the soil resistance to both detachment and transport (Morgan, 1995). The

resistance is associated with soil type. Some types of soil are more sensitive to erosion than theother. As an example, lithosol is very sensitive to erosion. Andosol is more sensitive to erosionthan latosol (Legal Document of Ministry of Agriculture number 837/Kpts/UM/11/1980 andnumber 683/Kpts/UM/8/1981).

Study area is laid upon several soil types. Those types are andosol (yellow brown andosol andbrown andosol), latosol (brown latosol and red brown latosol), lithosol, and brown mediteran.Andosol soil exists in volcanic cone of Lawu Volcano, lower slope of Mount Sidoramping, andsmall valley in Sidoramping lava. Latosol soil can be found in lower part of Lawu Volcano (Lawulahar plain, moderate hill in Sidoramping lava flow, low hill in volcanic rock formation, rivervalley, front slope of Lawu Volcano, eroded volcanic cone, undulating terrain in lava flow, andandecite hill). Lithosol is located in high hill of Sidoramping lava flow while brown mediteran soilis only located in limestone hill.

The erodibility index in this research is estimated by using soil type approach. Secondary datafrom previous research and literature are employed (Table 5.3 and Table 5.4). The achievederodibility index data is then linked with landform as a mapping unit. The result shows that thestudy area consists of two erodibility classes, i.e. low (0.11 – 0.20) and moderate (0.21 – 0.32)(Table 5.5). Low erodible areas are concentrated in northern part of study area whereas moderateerodible areas are situated in southern part (Figure 5.2).

Table 5.3. Erodibility Index Based on Soil Type and Geological FormationSoil Type Geology Formation Erodibility Index

Andosol Lawu Lahar (Qlla)Lawu Volcanic Rock (Qvl)Sidoramping Lava (Qvsl)Jobolarangan Breccia (Qvjb)Condrodimuko Lava (Qvcl)Wonosari Formation (Tmwl)

0.150.160.140.190.190.17

Latosol Lawu Lahar (Qlla)Lawu Volcanic Rock (Qvl)Sidoramping Lava (Qvsl)Andecite (Tma)Wonosari Formation (Tmwl)

0.190.170.230.170.17

Mediteran Lawu Lahar (Qlla)Lawu Volcanic Rock (Qvl)

0.210.16

Lithosol Jobolarangan Breccia (Qvjb) 0.20Source: Hartono (2008)

Table 5.4. Erodibility Index Based on Soil TypeSoil Type Erodibility Index Soil Type Erodibility Index

Red Latosol 0.12 Gley Humic 0.13

Yellow Red Latosol 0.26 Gley Humic 0.26

Brown Latosol 0.23 Gley Humic 0.20

Latosol 0.31 Lithosol 0.29

Regosol 0.12 – 0.16 Grumusol 0.21

Regosol 0.29 Grey Hydromorf 0.20

Regosol 0.31Source: Asdak (2007)


Page | 49

Table 5.5. Erodibility Class for Each LandformLandform Soil Type – Geological

FormationErodibility Index –Erodibility Class

Volcanic cone of Lawu Volcano Yellow Brown Andosol - Qvl 0.16 - KE2

Lower slope of Mount Sidoramping Brown Andosol - Qvjb 0.19 - KE2

Undulating terrain in lava flow Brown Latosol - Qvl 0.17 - KE2

High hill in Sidoramping lava flow Lithosol - Qvsl 0.29 - KE3

Moderate hill in Sidoramping lava flow Brown Latosol - Qvsl 0.23 - KE3

Low hill in volcanic rock formation Brown Latosol - Qvl 0.17 - KE2

Small valley in Sidoramping lava Brown Andosol - Qvsl 0.14 - KE2

River Valley Brown Latosol - Qlla 0.19 - KE2

Eroded Volcanic cone Brown Latosol - Qvl 0.17 - KE2

Front slope of Lawu Volcano Brown Latosol - Qvl 0.17 - KE2

Lawu lahar plain Brown Latosol - Qlla 0.19 - KE2

Andecite hill Red Brown Latosol - Tma 0.17 - KE2

Limestone hill Brown Mediteran - Tmwl 0.21 - KE3Source: Data Analysis (2009)

c. Actual erosionErosion can be defined as the process of detachment and movement of soil material. The

process of erosion is controlled by local landscape and weather conditions (USDA, 1993). Thosefactors determine the erosion velocity in a certain area. In addition, erosion is also influenced byhuman intervention. Improper agricultural land use practice can force rapid erosion.

Actual erosion represents common condition of eroded area. Those conditions can beassociated with drainage density and sparse vegetation/bare land distribution. Besides, soil type isalso related to soil sensitivity to erosion. Thereby, those three variables are assumed as clues inaccordance with actual erosion in study area.

Drainage density means the quotient of cumulative stream length to the total drainage area.This variable is stated in length per unit area (Choubey and Jain, 1992). The higher drainagedensity stands for a rapid storm response and a favorable condition for higher erosion from thecatchment (Jain and Goel, 2002). In this research, drainage density is classified into three classes,i.e. low (less than 1.80 km/km2), moderate (1.80 – 2.58 km/km2), and high (more than 2.58km/km2). The classes are symbolized by code L, M, and H respectively.

Vegetation has a basic function as a protective layer between the atmosphere and the soil(Morgan, 1995). The existence of leaves reduces the velocity of rainfall because of the ability toabsorb the energy of rain drops. It means that the power of rainfall in detaching the soil is gettinglower. Thereby, the wider the width area of sparse vegetation/bare land represents the higherprobability of erosion. The distribution of sparse vegetation/bare land is obtained from present landuse map.

Soil type determines the sensitivity level to erosion. The physical properties of each soil typeinfluence the infiltration capacity and to which extent the soil can be detached, dispersed, andtransported (Jain and Goel, 2002). Lithosol, as an example, is shallow soil which exists upon hardrock. The development of this soil is hampered due to severe erosion. The classification of soilsensitivity to erosion is adapted from Legal Document of Ministry of Agriculture number837/Kpts/UM/11/1980 and number 683/Kpts/UM/8/1981 (Table 2.4).

The combination of three variables gives some conclusions. The study area comprises withthree actual erosion classes, i.e. minor (e1), moderate (e2), and moderately severe erosion (e3).Minor erosion occurs in five landforms while moderate erosion happens in six landforms. Themoderately severe erosion only pervades two landforms (volcanic cone of Lawu Volcano and highhill in Sidoramping lava flow) since those landforms have all erosion clues (medium drainagedensity, the existence of sparse vegetation/bare land, and sensitive soil to erosion). Theclassification of actual erosion for study area is presented in Figure 5.3 and Table 5.6.


Page | 50

Figure 5.2. Erodibility Index Map of Tawangmangu Sub District

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Map 13Erodibility Index of Tawangmangu Sub District

Erodibility Index Class

Low (0.11 - 0.20)

Moderate (0.21 - 0.32)

East JavaProvince




Landform Boundary

River

Seasonal River

Province Boundary

Sub-district BoundaryDATUM: WGS1984


E rodibi li ty index was taken from literature study andprevious research, i.e. Asdak (2007) and Har tono (2008).

The obtained index was adopted by considering lithology and

soil type at each landform in study area .N

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Figure 5.3. Actual Erosion Map of Tawangmangu Sub District

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Map 14Actual Erosion of Tawangmangu Sub District

Actual Erosion Class

Minor Erosion

Moderate Erosion

Moderately Severe Erosion




East JavaProvince

Landform Boundary

River

Seasonal River

Province Boundary


DATUM: WGS 1984


Actual erosion was analyzed by using three factors

(dra inage density, dis tribution of bare land/sparse vegetation,and soi l type). The characteristic of those factor s in each

landform was then associated with

USDA erosion c lassification.

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Page | 51

Table 5.6. Actual Erosion Class for Each LandformLandform Drainage

Density(km/km2)

Percentageof Sparse

Vegetation/Bare Land

Soil Type*(Generalized)

ActualErosion

Class

Volcanic cone of Lawu Volcano 2.56/ M 2.30 Andosol / S e3

Lower slope of Mount Sidoramping 3.27/ H - Andosol / S e2

Undulating terrain in lava flow 2.51/ M - Latosol / LS e1

High hill in Sidoramping lava flow 1.94/ M 9.77 Lithosol / VS e3

Moderate hill in Sidoramping lava flow 2.82/ H - Latosol / LS e2

Low hill in volcanic rock formation 2.48/ M - Latosol / LS e1

Small valley in Sidoramping lava 4.73/ H - Andosol / S e2

River Valley 5.54/ H - Latosol / LS e2

Eroded Volcanic cone 2.89/ H - Latosol / LS e2

Front slope of Lawu Volcano 0.16/ L - Latosol / LS e1

Lawu lahar plain 1.02/ L - Latosol / LS e1

Andecite hill 2.76/ H - Latosol / LS e2

Limestone hill 1.78/ L - Mediteran / MS e1*Sensitivity to erosion, i.e. LS: Less Sensitive; MS: Moderately Sensitive; S: Sensitive; VS: Very SensitiveSource: Data Analysis (2009)

d. Soil depthSoil depth has general pattern concerned with topographic circumstance. Soil in foot slope area

is usually deeper than upper slope area (Wahyuningrum et al, 2003). This situation is triggered bythe more intensive erosion processes in upper part. The upper part becomes detachment area andlower part as depositional area.

The soil depth land capability concept has two functions. First, soil depth is related to the spacefor root penetration. Second, the soil depth influences the growth of crops associated with theability in providing water and supporting material. It means that deep soil is needed in landprocessing manner for agricultural purpose. The shallow soil will hamper intensive land utilization.

The study area mainly consists of soil depth of more than 90 cm (deep). Almost all landformshave deep soil. The very shallow soil (less than 25 cm) is only found in andecite hill and limestonearea. In this area, the soil is formed by organic materials. Those organic materials are emanatedfrom decaying leaves.

e. Soil textureSoil texture is defined as to the proportion of the various particle size classes in a certain soil

volume (FAO, 2006). The size refers to the diameter of soil fragment (sand, silt, and clay). Thediameter of sand is the biggest size, i.e. 0.05 - <2 mm. The diameter of silt fragment silt is 0.05 –0.002 mm and clay is less than 0.002 mm.

Soil texture is one of important considerations in utilizing the land. Texture affects the soilcapacity to keep the water as a vital substance for crops. Soil fragment with big diameter size tendsto rapidly release the water. Therefore, sandy soil is not appropriate for agricultural purpose since itcannot retain the water for supporting the growth of plant.

The condition of soil texture in study area is concerned with geological and topographiccondition. The geological formation in study area is affected by volcanic activity. The volcanicmaterial is characterized by fine grained and the existence of glass (Munir, 2003). Andecite withfine grained structure dominates almost all areas. It is mixed with other volcanic materials, forinstance volcanic sand (Lawu lahar), and volcanic tuff and breccia (Lawu volcanic rock). Thiscondition puts sand and silt as dominant fragment in soil texture. On the other hand, topographicsituation is also affects soil texture. Steep slope area has coarser soil texture than relatively flat area(Wahyuningrum, et. al, 2003). It is caused by detachment process of fine materials in steep area.The fine materials are then deposited in flat zone. Medium structure (loam) in study area largelyexists in steep slope area, for example, volcanic cone of Lawu Volcano and high hill inSidoramping lava flow while moderate fine texture (clay loam) is found in flat area.


Page | 52

Tawangmangu Sub District generally consists of four texture classes. Those are clay (moderatehill in Sidoramping lava flow and low hill in volcanic rock formation), clay loam (Lawu laharplain, river valley, andecite hill, and limestone hill), loam (volcanic cone of Lawu Volcano, lowerslope of Mount Sidoramping, high hill and small valley in Sidoramping lava flow, eroded volcaniccone, and front slope of Lawu Volcano), and sandy loam (undulating terrain in lava flow).

f. Soil permeabilitySoil permeability is associated with soil texture. The coarser texture is fairly inclined to show

faster permeability compared with fine texture. It means that sandy soil has higher permeabilitythan silty and clayey soil since sandy soil is coarser than silty and clayey soil.

The permeability is one of significant points for intensive land use purpose. Moderate orsomewhat slow permeability are relatively more needed in correlation with the soil ability forretaining the water. Soil with fast permeability cannot intensively used because the soil is not ableto provide adequate water for the growth of crop.

Soil permeability in study area is commonly moderately slow and moderately fast. Thissituation explicitly supports the intensive land utilization in study area. Slow permeability areasonly exist in river valley and moderate hill in Sidoramping lava flow. The areas with moderatelyslow permeability pervade andecite hill, limestone hill, Lawu lahar plain and low hill in volcanicrock formation. Besides, soil with moderately fast permeability exists in four landforms, i.e.undulating terrain, high hill and small valley in Sidoramping lava flow, and eroded volcanic cone.The rest areas are classified as fast permeability areas.

g. Soil drainageSoil drainage describes air circulation and water movement in the soil. The soil drainage

condition can be recognized from the appearance of particular color spot, i.e. yellow, brown, orgrey. The color is associated with corrosion process in the soil due to water concentration. Thecloser the existence of color spot to the surface depicts the worse soil drainage in a given location.

Soil drainage is linked with topographic condition and lithology. Bowl-shaped and flat areausually has worse drainage than sloping area. In bowl-shaped area, water inundate for a long timewhereas in sloping area, water dynamically moves. In study area, most areas with sloping situationare classified as well drained area. There is no color spot emergence in those areas. Nevertheless,some areas are categorized as poorly drained area, i.e. andecite hill, Lawu lahar plain, and rivervalley. Those areas are typified with relatively flat and bowl-shaped areas. Concerned withlithology, the parent material also determines the soil drainage. The area composed by limestonequickly releases the water (Wahyuningrum et al, 2003). This condition exists in study area atwhich limestone hill in Tawangmangu Sub District belongs to excessively drained area (Figure5.4).

h. Rock fragmentRock fragment implicates the existence of rock both on the surface and in the soil. Those

conditions affect the capability of the land for intensive land use practice. The number of rockoutcrops on the surface is corresponded to erosion process. If the number of rock outcrops isgetting bigger, the erosion process is also more intense. Hence, the land is less suitable to be usedas agricultural land. In addition, rock fragment in the soil hampers the root penetration disturbs thegrowth of plant. The distribution of coarse fragment in the soil and on the surface decreases landquality for cultivation purpose. It declines the width of cultivated area because a certainagricultural practice cannot be conducted

This study is focused on the condition of rock fragment in the soil. The distribution of coarsefragment in the soil is estimated by using the chart as shown in Figure 2.3. As a result, it is only asmall number of coarse fragments in the soil for most areas. A moderate percentage of coarsefragments are located in low hill in volcanic rock format, small valley in Sidoramping lava flow,and front slope of Lawu Volcano. On the other side, a fair much of coarse fragments exist inandecite hill (50-90% of soil volume) and limestone hill (>90% of soil volume) (Figure 5.5).


Page | 53

Figure 5.4. Soil Drainage Map of Tawangmangu Sub District

507000

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Meters



Lawu Lahar Plain



Andecite Hill

Limestone Hill


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mE

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Map 15Soil Drainage of Tawangmangu Sub District

Land Drainage Class

Excessivelly Drained

Poorly Drained

Well Drained

East JavaProvince





2. Field Checking (2009)

Landform Boundary

River

Seasonal River

Province Boundary


DATUM: WGS1984


Soil drainage map was made by classi fying soi l drainagecondition in each landfo rm observed during the field work.

Soil drainage was recognize by the apperance of

some color spots (ye llow, br own, or grey) in the soil .N

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Figure 5.5. Rock Fragment Map of Tawangmangu Sub District

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mE

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Map 16Rock Fragment of Tawangmangu Sub District

Rock Fragment Class

Moderate (15-50% of soil volume)

Much (50-90% of soil volume)

No (0-15% of soil volume)

Very Much (>90% of soil volume)




East JavaProvince

Landform Boundary

River

Seasonal River

Province Boundary


DATUM: WGS1984


Rock fragment map used the result of soil observation.Rock fragment at several samples in each landform was

observed in order to get common condition of rock fragm ent

in every landform.N

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Page | 54

i. Landslide susceptibilityLandslide is a common hazard in study area. This hazard reveals as a consequence of slope

instability. One of causal factors in slope instability is related to improper land use practice.Therefore, landslide information is required to be implicated in land capability assessment as a wayin determining more suitable land use practice.

Landslide susceptibility is a new parameter in proposed land capability classification. Thisparameter plays as one of hindering factors in conducting a certain land use practice. If landslidesusceptibility is well recognized, more comprehensive land capability and proper land use practicecan be established to minimize future risk due to landslide threat.

Study area has been classified into five landslide susceptibility classes. Each landslidesusceptibility class is randomly dispersed. One dominant class in each landform is decided as arepresentative value. As a result of generalization process, study area consists of three dominantlandslide susceptibility classes, i.e. low, moderate, and high. Low susceptible areas exist inrelatively flat zone (lower slope of Mount Sidoramping, small valley in Sidoramping lava, Lawulahar plain, and andecite hill). Moderate susceptible zones are positioned in undulating terrain inlava flow, high hill in Sidoramping lava flow, river valley, and limestone hill. The rest areas arecategorized as high susceptible to landslide.

Land Capability AssessmentLand capability assessment was done by matching technique. All parameters are corresponded

with proposed land capability classification. The result shows that study area generally consists of fourclasses, i.e. class IV, VI, VII, and VIII (Figure 5.6). The worst condition in each class is then added assub class. The worst situation mainly refers to soil depth, permeability, slope, and landslidesusceptibility so that sub class “s” and “e” are assigned to those land capability classes. Thereby, landcapability class and subclass for study area comprises with IVe, VIe, VIs, VIIe, VIIIe, VIIIs, and VIIIw(Table 5.7). The detailed explanation of land capability class and sub class is presented below.

Table 5.7. General Land Capability Class and Subclass for Tawangmangu Sub DistrictLandform Inhibiting Factors* Class and

Subclass1 2 3 4 5 6 7 8 9

Volcanic cone of Lawu Volcano G KE2 e3 k0 t3 p5 d1 b0 LS4 VIIIe

Lower slope of Mount Sidoramping D KE2 e2 k0 t3 p5 d1 b0 LS2 VIIIs

Undulating terrain in lava flow D KE2 e1 k0 t4 p4 d1 b0 LS3 VIe

High hill in Sidoramping lava flow G KE3 e3 k0 t3 p4 d1 b0 LS3 VIIIe

Moderate hill in Sidoramping lava flow F KE3 e2 k0 t1 p1 d1 b0 LS4 VIIe

Low hill in volcanic rock formation D KE2 e1 k0 t1 p2 d1 b1 LS4 VIIe

Small valley in Sidoramping lava D KE2 e2 k0 t3 p4 d1 b1 LS2 IVe

River valley D KE2 e2 k0 t2 p1 d4 b0 LS3 VIe

Eroded volcanic cone G KE2 e2 k0 t3 p4 d1 b0 LS4 VIIIe

Front slope of Lawu Volcano D KE2 e1 k0 t3 p5 d1 b1 LS4 VIIIe

Lawu lahar plain C KE2 e1 k0 t2 p2 d4 b0 LS2 IVe

Andecite hill D KE2 e2 k3 t2 p2 d4 b2 LS2 VIs

Limestone hill D KE3 e1 k3 t2 p2 d0 b3 LS3 VIIIw*1=slope, 2=erodibility, 3=actual erosion, 4=soil depth, 5= texture, 6=permeability, 7=soil drainage, 8=rock fragment,9=landslide susceptibility.Source: Data Analysis (2009)

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Page | 56

Class IV implicates the area in Lawu lahar plain and small valley in Sidoramping lava flow.Lawu lahar plain area is characterized by minor erosion (e1), moderately fine texture (t2), andmoderately slow permeability (p2), poorly drained (d4), and low susceptible to landslide (LS2). Thearea generally has several supporting factors for land use practice but low susceptible to landslidereduces its capability for intensive purpose. On the other hand, small valley area basically hascircumstances that allows for intensive land use, i.e. deep soil (k0), medium texture (t3), moderately fastpermeability (p4). Nonetheless, the implementation of land utilization shall consider hilly conditionwhich is possible to be unstable. Those characteristics show that low susceptible to landslide acts as themain adverse factors in Lawu lahar plain whereas hilly slope is the most constraint factor in small valleyarea. Thus, all areas in class IV are joined in sub class IVe.

Three landforms in study area are classified in class VI. Those are undulating terrain in lavaflow, river valley, and andecite hill. Undulating terrain is typified by low erodibility (KE2), deep soil(k0), well drained (d1), less than 15% of rock fragment (b0), and moderate susceptible to landslide(LS3). River valley area has several characteristics, i.e. moderate erosion (e2), poorly drained (d4), andmoderate susceptible to landslide (LS3). The present condition reveals that moderate susceptible tolandslide is the major constraint factor in both landforms. Thus, undulating terrain and river valley areclassified in sub class VIe. On the other side, andecite hill has different main limitation. Very shallowsoil (less than 25 cm) in this area hinders exhaustive land use. The very shallow soil decreases landcapacity for providing water, supporting material, and space for root penetration. Therefore, this area isincluded in sub class VIs.

Land capability class VII pervades two landforms, i.e. moderate hill of Sidoramping lava flowand low hill in volcanic rock formation. Moderate hill area exists in steep slope (F) with moderateerodibility (KE3), moderate erosion (e2), and high susceptible to landslide (LS4). Low hill area istypified by hilly area (D), low erodibility (KE2), moderate appearance of rock in the soil (b1), and highsusceptible to landslide (LS4). Those situations describe that slope and high susceptible to landslide arethe highest hindering factor for moderate hill and low hill area respectively. Hence, both landforms areassigned sub class VIIe.

Class VIII is the most dominant land capability class in study area. This class covers sixlandforms, i.e. volcanic cone of Lawu Volcano, high hill in Sidoramping lava flow, eroded volcaniccone, lower slope of Mount Sidoramping, front slope of Lawu Volcano, and limestone hill. In volcaniccone of Lawu Volcano, very steep slope (G), fast permeability (p5), and high susceptible to landslide(LS4) obstruct intensive land use practice in this area. The high hill in Sidoramping lava flow anderoded volcanic cone are also deterred by very steep slope. Hence, those three landforms are categorizedin sub class VIIIe since slope acts as the major impediment factor. On the other hand, lower slope ofMount Sidoramping is characterized by low erodibility (KE2), deep soil (k0), medium textured (t3),well drained (d1), and fast permeability (p5). Land use practice in front slope is hampered by fastpermeability (p5) as well. Based on the existing of fast permeability factor, both landforms are includedin sub class VIIIs. In addition, limestone hill is getting worse due to excessively drained condition (d0)so that this landform is categorized as sub class VIIIw.

5.5. Detailed Land Capability Class Based on Proposed MethodDetailed land capability assessment is an effort to specify the general land capability class to

obtain more elaborate result. This analysis takes an assumption that one general land capability classcomprises some detailed land capability classes. It is associated with the spatial distribution of slope andlandslide susceptibility. The elaborate class reveals the possibility in establishing more comprehensiveland use.

Detailed land capability assessment employs the result from general land capability appraisal.The detailed class is obtained by overlying general land capability class with slope and landslidesusceptibility class. The result is then matched with proposed land capability classification. Theflowchart of detailed land capability assessment is depicted in Figure 5.7.

The detailed assessment gives different result compared with general version. Study areaconsists of six land capability classes, i.e. class III, IV, V, VI, VII, and VIII. Several areas can beelaborated into several classes while the others are not. This circumstance is caused by the mainconstraint factor in the given areas. Five landforms (volcanic cone in Lawu Volcano, lower slope ofMount Sidoramping, front slope of Lawu Volcano, andecite hill, and limestone hill) have majorlimitation related to soil properties. The most constraint in three landforms (volcanic cone in Lawu


Page | 57

Volcano, lower slope of Mount Sidoramping, and front slope of Lawu Volcano) are fast permeabilitywhereas limestone hill is hampered by excessively drained condition. The existing limitationsautomatically classify those areas as class VIII. Besides, andecite hill areas are still categorized as classVI even though this area is typified by relatively hilly area and low landslide susceptibility. In this case,very shallow soil still acts as the most constraint in andecite hill. On the other hand, other landforms instudy area can be itemized into various classes. Low hill in volcanic rock formation, as an example, isformerly categorized as class VII. This area is then specifically divided into three classes, i.e. class VI,VII, and VIII. The width area for each class is 73 Ha, 434 Ha, and 259 Ha respectively. Anotherexample is eroded volcanic cone area. This landform consists of three specified classes, i.e. class VI,VII, and VIII although this area is previously categorized as class VIII (Table 5.8). Those resultsdescribes that detailed land capability assessment is able to provide more elaborate information formanaging the land. The spatial distribution of detailed land capability class can be harnessed forestablishing more comprehensive land use planning. The detailed land capability class is illustrated inFigure 5.8.

Table 5.8. Detailed Land Capability Class Based on Proposed MethodLandform General Land

Capability ClassDetailed Land Capability Class

and Width Area (Ha)

Volcanic cone of Lawu Volcano VIII VIII (2,134)

Lower slope of Mount Sidoramping VIII VIII (140)

Undulating terrain in lava flow VI IV (22), VI (179), VII (36), VIII (8)

High hill in Sidoramping lava flow VIII IV (47), VI (163), VII (437), VIII (792)

Moderate hill in Sidoramping lava flow VII VI (349), VII (355), VIII (204)

Low hill in volcanic rock formation VII VI (73), VII (434), VIII (259)

Small valley in Sidoramping lava IV III (13), IV (81), VI (32), VII (26), VIII (8)

River valley VI V (6), VI (78), VII (6), VIII (23)

Eroded volcanic cone VIII VI (21), VII (38), VIII (38)

Front slope of Lawu Volcano VIII VIII (121)

Lawu lahar plain IV IV (378), VI (266), VII (8)

Andecite hill VI VI (116)

Limestone hill VIII VIII (112)Source: Data Analysis (2009)

SlopeErodibility

Actual ErosionSoil Depth

Soil TextureSoil Permeability

Soil drainageRock Fragment

Landslide SusceptibilityOverlayandMatching

Generalization

LandCapabilityClass

DetailedLandCapabilityClass

Figure 5.7. Flowchart of Detailed Land Capability Assessment

Matching

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susceptibility

GeneralVersion

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Page | 59

5.6. The Other Alternative in Land Capability AssessmentAn alternative method is applied in integrating landslide susceptibility into land capability

assessment. This method harnesses the similar constraint factors. However, landslide susceptibility isnot directly included in estimating land capability. The susceptibility information is added after landcapability class is obtained. It is intended to specify land capability class by considering the distributionof landslide susceptibility. The flowchart of an alternative method is depicted in Figure 5.9.

This method reveals some general results. There are four landforms included in class IV, i.e.undulating terrain, low hill in volcanic rock formation, small valley in Sidoramping lava, and Lawulahar plain. The most constraint factor in those landforms is hilly situation. It is only Lawu lahar plainarea that is hampered by poorly drained condition. Class V just pervades river valley area. The rivervalley area is typified by slow permeability. Andecite hill area is classified as class VI whilst moderatehill in Sidoramping lava flow is categorized in class VII. Land use practice in andecite hill is obstructedby very shallow soil condition while moderate hill area is hindered by steep slope. In addition, the restareas in Tawangmangu Sub District are included in class VIII.

This method also shows several specified results. Some landforms can be elaborated intoseveral classes. Undulating terrain area consists of three specified classes, i.e. class IV, VI, and VII. Thesimilar situation as in undulating terrain area exists in Lawu lahar plain. The general land capabilityclass in low hill area is specified into three classes, i.e. class VI, VII, VIII. Small valley area iscategorized into class IV and class VI whereas river valleys areas are detailed into class V, VI, VII, andVIII. Those results illustrate that the elaboration process tends to give higher land capability classes. Asa case, if a certain landform is formerly classified as class IV, the improved land capability class cancomprise class IV, VI, and VII. The complete result of this method is described in Table 5.9 and it isportrayed in Figure 5.10.

Table 5.9. Land Capability Class Based on Alternative MethodLandform Land Capability

ClassSpecified Land Capability Class and

Width Area (Ha)

Volcanic cone of Lawu Volcano VIII VIII (2,134)

Lower slope of Mount Sidoramping VIII VIII (140)

Undulating terrain in lava flow IV IV (22), VI (183), VII (40)

High hill in Sidoramping lava flow VIII VIII (1,439)

Moderate hill in Sidoramping lava flow VII VII (908)

Low hill in volcanic rock formation IV VI (72), VII (433), VIII (259)

Small valley in Sidoramping lava IV IV (115), VI (45)

River valley V V (6), VI (78), VII (5), VIII (24)

Eroded volcanic cone VIII VIII (97)

Front slope of Lawu Volcano VIII VIII (121)

Lawu lahar plain IV IV (378), VI (266), VII (8)

Andecite hill VI VI (116)

Limestone hill VIII VIII (112)Source: Data Analysis (2009)

Constraint Factors:Slope

ErodibilityActual Erosion

Soil DepthSoil Texture

Soil PermeabilitySoil drainage

Rock Fragment

Landslide Susceptibility

OverlayandMatching

MatchingLandCapabilityClass

ImprovedLandCapabilityClass

Figure 5.9. Flowchart of an Alternative Method


Page | 60

Some areas cannot be elaborate into specified land capability. The worst situation hampersthose areas to be elaborated into various classes. This situation occurs in eight landforms, i.e. volcaniccone of Lawu Volcano, lower slope of Mount Sidoramping, high hill in Sidoramping lava flow,moderate hill in Sidoramping lava flow, eroded volcanic, front slope of Lawu Volcano, andecite hill,and limestone hill. Steep and very steep slope, fast permeability, very shallow soil, and excessivelydrained condition hinder intensive land use practice. On the other word, landslide susceptibility factordoes not have influence in determining specified land capability class in the given areas.

The next discussion in this research does not use the result from alternative method. Thistechnique does not give more detail result compared with proposed method. Even so, the alternativemethod can be still harnessed as an optional way in elaborating general land capability class in a certainarea.

Figure 5.10. Land Capability Map of Tawangmangu Sub District Based on Alternative Method

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DATA SOURCE:

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Scale 1:25,000 (2001)2. Field Checking (2009)3. Soil Laboratory Analysis (2009)


LEGEND:

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Meters



Lawu Lahar Plain



Andecite Hill

Limestone Hill


River Valley





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Map 19Land Capability of Tawangmangu Sub District

Based on Alternative Method

VII

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Landform Boundary

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Page | 61

CHAPTER VILAND USE FUNCTION OF TAWANGMANGU SUB DISTRICT

This chapter specifies the previous chapter by applying the result of land capability assessment indetermining land use function. Land use function division based on government’s method is also done.Both methods are developed in general and detailed version. The result from both methods is thendescriptively compared.

6.1. IntroductionLand use function is a general zoning of land. It distinguishes a certain area into three

functions, i.e. protected, buffer, and cultivated area. The division of land use function is employed todetermine the further land utilization. Each land use function shall be exploited for appropriate land usein order to keep the sustainable usage.

Spatial planning in Indonesia applies land use function as a basis in determining proper landuse. All spatial planning documents implicate land use function analysis for arranging further land usein a given area. In government view, land use function is determined by using scoring method fromMinistry agriculture. Meanwhile, land use function in this research is recognized as an expanded resultof land capability assessment.

6.2. Land Use Function Developed by Local GovernmentKaranganyar Regency has emphasized the involvement of land use function analysis in spatial

planning. RTRW of Karanganyar Regency 1997-2006 and RDTRK of Tawangmangu 2007-2016 assertthat land use function in Karanganyar Regency is derived through land capability assessment. The landcapability appraisal is conducted by scoring method. This method is declared on Legal Document ofMinistry of Agriculture number 837/Kpts/UM/11/1980 (Anonymous, 1980) and number683/Kpts/UM/8/1981 (Anonymous, 1981). Scoring method uses three variables i.e. slope, soil type, andaverage daily rainfall intensity. Each variable is elaborated into several classes as shown in Table 2.3 –2.5. The classes are given a certain score which is then accumulated to divide a certain area into threeland use functions, as follow: Protected area involves the area with score of ≥ 175. Protected area is provided for natural preserve

purpose. Buffer area includes the area with score of 125-174. The buffer area has double functions, as

protected or cultivated area. However, cultivation activity is not as intense as cultivated area. Cultivated area is applied for the area with score of less than 125. Cultivated area itself consists of

yearly and seasonal cultivated area. For settlement area, there is an additional requirement which isthe slope must be less than 8%.

The land use function division in RTRW of Karanganyar Regency is illustrated in the allocationmap of protected area and cultivated area. The allocation map of protected area (Figure 6.1) depicts thatprotected area is specified into protected forest area, protected hydrology area, special area, cultural lifearea, river side area, water spring area, and dam area. On the other side, allocation map of cultivatedarea (Figure 6.2) itemizes cultivated area into nine classes, i.e. urban settlement area, rural settlementarea, wet land area, dry land area, yearly cultivated area, production forest area, industrial estate,industrial development area, and industrial zone. Based on those maps, Tawangmangu Sub District ismostly assigned as protected forest area, especially in northern and southern part. The middle part isproposed as yearly cultivated area and urban settlement area

RDTRK of Tawangmangu has developed land capability analysis for development area ofTawangmangu. The mapping area involves three villages, i.e. Tawangmangu, Kalisoro, and Nglebak.The analysis states that the range of score is from 90 to 165 so that those areas are possible to bedeveloped as settlement area, seasonal cultivated area, yearly cultivated area, and buffer area. Thepresent land use function division in RDTRK unfortunately does not encompass the whole area inTawangmangu Sub District. Thereby, land use function map generated with scoring method isperformed to overcome the lack of data for the whole study area.


Page | 62


Figure 6.2. Allocation Map of Cultivated Area in Regency Scale (BAPPEDA, 1997)


Figure 6.1. Allocation Map of Protected Area in Regency Scale (BAPPEDA, 1997)


Page | 63

6.3. Development of General Land Use FunctionGeneral land use function is generated by using landform as a land mapping unit. This mapping

unit is applied to both methods, i.e. Ministry of Agriculture’s method (scoring method) and proposedmethod. By using the similar analysis unit, the result from both methods can be properly compared. Thecomparison itself is intended to descriptively define the differences between both methods.

6.3.1. General Land Use Function Based on Ministry of Agriculture’s Method (ScoringMethod)Scoring method makes use of three variables (slope, soil type, and average daily rainfall

intensity). Slope in this research is developed from contour data derived from topographic map whilesoil type is taken from soil map (Appendix 2). Average daily rainfall is calculated from daily rainfallintensity for 23 years (1986-2008). The rainfall data is achieved from Somokado gauge (TawangmanguVillage) since this is the one functioned gauge in study area. All required variables are classified andgiven a certain score. The score is amassed for identifying land use function.

The obtained score is in the range of 90 – 195 (Table 6.1). It means that study area can bedivided into three land use functions. Protected area comprises 51% of total area (3,573 Ha). Buffer andcultivated area pervades 31% (2,183 Ha) and 18% (1,247 Ha) of total area respectively. Protected andbuffer areas spatially exist in northern, southern, and eastern part of Tawangmangu Sub District. Therest areas are assigned as cultivated area. In relation with landform, two landforms (volcanic cone ofLawu volcano and high hill in Sidoramping lava flow) are classified as protected area. Six landforms(lower slope of Mount Sidoramping, moderate hill in Sidoramping lava flow, low hill in volcanic rockformation, small valley in Sidoramping lava, eroded volcanic cone, and limestone hill) are included inbuffer area and the rest five landforms are allocated as cultivated area. Land use function distributionbased on Ministry of agriculture’s method is portrayed in Figure 6.3.

Table 6.1. Land Use Function Based on Ministry of Agriculture’s Method

Landform

Characteristic and Score

TotalLand UseFunctionSlope Soil Type Daily

Rainfall

Volcanic cone of LawuVolcano

>45%(100)

Andosol(60)

18 mm/day(20)

180 Protected area

Lower slope of MountSidoramping

15 – 25%(60)

Andosol(60)

18 mm/day(20)

140 Buffer area

Undulating terrain in lavaflow

8– 15%(40)

Latosol(30)

18 mm/day(20)

90 Cultivated area

High hill in Sidoramping lavaflow

>45%(100)

Litosol(75)

18 mm/day(20)

195 Protected area

Moderate hill in Sidorampinglava flow

>45%(100)

Latosol(30)

18 mm/day(20)

150 Buffer area

Low hill in volcanic rockformation

25 – 45%(80)

Latosol(30)

18 mm/day(20)

130 Buffer area

Small valley in Sidorampinglava

15 – 25%(60)

Andosol(60)

18 mm/day(20)

140 Buffer area

River valley 15 – 25%(60)

Latosol(30)

18 mm/day(20)

110 Cultivated area

Eroded volcanic cone >45%(100)

Latosol(30)

18 mm/day(20)

150 Buffer area

Front slope of Lawu Volcano 15 – 25%(60)

Latosol(30)

18 mm/day(20)

110 Cultivated area

Lawu lahar plain 8 – 15%(40)

Latosol(30)

18 mm/day(20)

90 Cultivated area

Andecite hill 15 – 25%(60)

Latosol(30)

18 mm/day(20)

110 Cultivated area

Limestone hill 15 – 25%(60)

Mediteran(45)

18 mm/day(20)

125 Buffer area

Source: Data Analysis (2009)


Page | 64

6.3.2. General Land Use Function Based on Proposed MethodProposed land capability classification has classified the study area into four general land

capability classes. The classes are IV, VI, VII, and VIII. The different land capability class is especiallyconcerned with different land management (land use function and land use practice). Hence, landcapability is used as basic information to discern appropriate land use manner.

Land capability class can be converted into particular land use function. The conversionanalysis utilizes the scheme of correlation between land capability and intensity of land use fromKlingebiel and Montgomery (1966) (Table 3.8). According to the given scheme, it can be assumed thatclass I – IV is classified in arable class while class V – VIII is included in non arable land. The arableland is proposed as cultivated area whereas non-arable land is supposed as buffer and protected area.For non-arable land, class V - VII is classified as buffer area because those classes can be used asnatural preserve/wildlife, limited production forest, and limited grazing. Class VIII is included asprotected area since it is only apportioned as natural preserve/protected forest.

The study area is commonly classified as non arable land. Nine landforms are included as non-arable area whilst the rest areas are possible to be developed for cultivation and built up area (Table 6.2.and Figure 6.4). The division of land use function in Tawangmangu Sub District is below explained:a. Protected area covers 58% of total area (4,043 Ha). It pervades volcanic cone of Lawu Volcano,

lower slope of Mount Sidoramping, eroded volcanic cone, front slope of Lawu Volcano, limestonehill, and high hill in Sidoramping lava flow. The areas are mostly hampered by slope and landslidesusceptibility. Thus, it is better to keep those areas in natural condition rather than to exploit theland.

b. Buffer area encompasses 31% of total area (2,148 Ha). This zone is located in several regions, i.e.undulating terrain in lava flow, river valley, moderate hill in Sidoramping lava flow, low hill involcanic rock formation, and andecite hill.

c. Cultivated area implicates 11% of total area (812 Ha). It is only two landforms that can be exploitedas cultivated area. Those areas are small valley in Sidoramping lava flow and Lawu lahar plain.

Table 6.2. Land Use Function Based on Proposed MethodLandform Class

andSubclass

GeneralCategory*

Land Use Intensity* Land UseFunction**

1 2 3 4 5 6 7 8 9

Volcanic cone of LawuVolcano

VIIIe Non Arable Protected area

Lower slope of MountSidoramping

VIIIs Non Arable Protected area

Undulating terrain in lava flow VIe Non Arable Buffer area

High hill in Sidoramping lavaflow

VIIIe Non Arable Protected area

Moderate hill in Sidorampinglava flow

VIIe Non Arable Buffer area

Low hill in volcanic rockformation

VIIe Non Arable Buffer area

Small valley in Sidorampinglava

IVe Arable Cultivatedarea

River valley VIe Non Arable Buffer area

Eroded volcanic cone VIIIe Non Arable Protected area

Front slope of Lawu Volcano VIIIe Non Arable Protected area

Lawu lahar plain IVe Arable Cultivatedarea

Andecite hill VIs Non Arable Buffer area

Limestone hill VIIIw Non Arable Protected area*Kliengebiel and Montgomery (1966), ** Ministry of Agriculture Regulation (1980/1981)1:wildlife, 2:forestry, 3:limited grazing, 4:moderate grazing, 5:intense grazing, 6:limited cultivation, 7:moderate cultivation,8:intense cultivation, 9:very intense cultivationSource: Data Analysis (2009)


Page | 65

6.3.3. The Comparison of General Land Use Function Developed by Scoring and ProposedMethodBoth methods reveal a quite similar result. Almost all areas have similar land use function.

Concerned with landform, five landforms are classified in the same land use function and the rest aredifferent (Table 6.3). The landforms with similar land use function are volcanic cone of Lawu Volcanoand high hill in Sidoramping lava flow. Both landforms are allocated as protected area. Besides,moderate hill and low hill areas are apportioned as buffer area while Lawu lahar plain is proposed ascultivated area.

The different land use function division can be also identified in some areas. Lower slope ofMount Sidoramping, eroded volcanic cone, and limestone hill are included as buffer area based onscoring method whereas they are categorized as protected area regarding to proposed method. Apartfrom that, undulating terrain in lava flow, river valley, and andecite hill are assigned as cultivated areasin scoring method and as buffer areas in proposed method. Front slope is categorized as protected areabased on proposed method. In scoring method, this area becomes a part of cultivated area. In addition,proposed method allocates small valley area as cultivated area while scoring method classifies this areaas buffer area.

Table 6.3. General Land Use Function ComparisonLandform General Land Use Function

Ministry of Agriculture’s Method/Scoring Method

Proposed Method

Volcanic cone of Lawu Volcano Protected area Protected area

Lower slope of Mount Sidoramping Buffer area Protected area

Undulating terrain in lava flow Cultivated area Buffer area

High hill in Sidoramping lava flow Protected area Protected area

Moderate hill in Sidoramping lava flow Buffer area Buffer area

Low hill in volcanic rock formation Buffer area Buffer area

Small valley in Sidoramping lava Buffer area Cultivated area

River valley Cultivated area Buffer area

Eroded volcanic cone Buffer area Protected area

Front slope of Lawu Volcano Cultivated area Protected area

Lawu lahar plain Cultivated area Cultivated area

Andecite hill Cultivated area Buffer area

Limestone hill Buffer area Protected areaSource: Data Analysis (2009)

The existing disparities implicitly affirm a particular problem. Scoring method is not clearenough in describing the worst situation obstructing intensive land utilization. This method merelyconsiders topographic situation and sensitivity to erosion as limitation factor in a certain area. On theother side, proposed method adds more comprehensive constraints. It is not only topographic anderosion, but hazard probability and soil properties as well. Nevertheless, both methods can accomplishone to another. The scoring method can be improved by identifying the most constraint as illustrated inproposed method. The improvement of scoring method is explained through following examples: Lower slope of Mount Sidoramping is classified as buffer area (scoring method) and as protected

area (proposed method). Proposed method allocates this area as protected region due to fastpermeability condition. It means that the function of buffer area as stated in scoring method has tobe conducted with special priority. The area can be used for limited land use practice but it mustdeliberate conservation concept.

Undulating terrain is implicated as cultivated area (scoring method) and buffer area (proposedmethod). Factor of moderate susceptible to landslide has to be taken into account as if this area willbe used as cultivation zone. The proper agricultural technique must be applied in order to avoidslope instability in this area.

Small valley in Sidoramping lava flow is categorized as buffer area (scoring method) and cultivatedarea (proposed method). This landform is quite suitable to be intensively exploited as cultivatedarea because it is supported by relative flat area and low susceptible to landslide.


Page | 66

Eroded volcanic cone is classified as buffer area (scoring method) and protected area (proposedmethod). Since buffer area is transition zone between protected and cultivated area; this area can beadvised to be reclassified as protected area by considering very steep slope as the major constraintin this landform.

Figure 6.3. General Land Use Function Map of Tawangmangu Sub District Based on Ministry of Agriculture’s Method

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DATA SOURCE:

LEGEND:

500 0 500 1000 1500 2000 2500

Meters



Lawu Lahar Plain



Andecite Hill

Limestone Hill


River Valley





mE

mE mE

mE

mN

mN

mN

mN

Map 20General Land Use Function of Tawangmangu Sub District

Based on Ministry of Agriculture's Method

Local

Footpath

Other

Collector

Road Class Land Use Function Classification

Buffer Area

Cult ivated Area

Protected Area

Province Boundary

Seasonal River

River

Landform Boundary

East JavaProvince







DATUM: WGS 1984


General land use function was mapped based on landform.The dominant value fo r three parameters (slope , soil type,

and aver age dai ly rainfall intensity) with a certain score

in each landformwas accumulated and converted intoparticular land use function, i .e. score of <125 (cultivated zone),

score of 125-174 (buffer zone), and score of >=175

( protected zone) .

N

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Figure 6.4. General Land Use Function Map of Tawangmangu Sub District Based on Proposed Method

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Limestone Hill


River Valley





mE

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Map 21General Land Use Function of Tawangmangu Sub District

Based on Proposed Method

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Cultivated Area

Buf fer Area

Land Use Function ClassificationRoad Class

Collector

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Footpath

Local







East JavaProvince

Landform Boundary

River

Seasonal River

Province Boundary

DATUM: WGS 1984


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and class VIII (protected zone)N

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Page | 67

6.4. Development of Detailed Land Use FunctionThe development of elaborate land use function is aimed to obtain more detail result compared

with general land use function. The specified result is an improvement to properly perform land usefunction division. In consequence, comprehensive land use planning for regional development can beappropriately done.

Detailed land use function is also generated by means of scoring and proposed method. Eachmethod still applies the similar variable. Detailed land use function through scoring method isconducted by directly overlying all variables. The slope is not generalized as done in general version.On the other hand, proposed method divides land use function by applying the result of detailed landcapability assessment.

6.4.1. Detailed Land Use Function Based on Ministry of Agriculture’s Method (ScoringMethod)The detailed version is proposed to spatially attain more specific location particular land use

function. It is assumed that one landform can be harnessed for more than one function due to spatialdistribution of slope. As a result, various land uses are possible to be performed in this area. In addition,the land can be effectively used.

The detailed version gives a quite different result compared with general version. This versionreveals the score range 70 – 195 while the general version has score range 90 – 195. Protected areas aremainly located in eastern part of study area. They are associated with high hill in Sidoramping lava flowand volcanic cone of Lawu Volcano. The areas are characterized by slope of more than 45% and soiltype of andosol and lithosol. On the other side, buffer areas are largely positioned in western part and atsome areas in eastern part. This zone exists in moderate hill in Sidoramping lava flow, low hill involcanic rock formation, and limestone hill. Buffer areas are typified by various slopes from flat to verysteep and latosol and mediteran as the main soil type. In addition, cultivated region covers less than20% of study area. It is generally situated in middle part of study area. The relative flat area and latosolas major soil type supports its function as a cultivated area. Width area for each land use function is2,659 Ha (38% of total study area) for protected area; 3,136 Ha (45% of total study area) for buffer area;1,208 Ha (17% of total study area) for cultivated area. The description of detailed land use functiondivision is presented in Table 6.4 and Figure 6.5.

Table 6.4. Distribution of Detailed Land Use Function Based on Ministry of Agriculture’s MethodLandform General Land

Use FunctionDetailed Land Use Function and

Width Area (Ha)

ProtectedArea

BufferArea

CultivatedArea

Volcanic cone of Lawu Volcano Protected area 1,150 878 106

Lower slope of Mount Sidoramping Buffer area 26 88 26

Undulating terrain in lava flow Cultivated area - 30 215

High hill in Sidoramping lava flow Protected area 1,427 12 -

Moderate hill in Sidoramping lava flow Buffer area - 902 6

Low hill in volcanic rock formation Buffer area - 697 69

Small valley in Sidoramping lava Buffer area 56 43 61

River valley Cultivated area - 97 16

Eroded volcanic cone Buffer area - 97 -

Front slope of Lawu Volcano Cultivated area - 76 45

Lawu lahar plain Cultivated area - 59 593

Andecite hill Cultivated area - 47 69

Limestone hill Buffer area - 110 2

Total 2,659 3,136 1,208Source: Data Analysis (2009)

6.4.2. Detailed Land Use Function Based on Proposed MethodDetailed land capability assessment has categorized the study area into several elaborate

classes. The specified class is acquired by spatially considering slope and landslide susceptibility


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distribution. These classes are class III, IV, V, VI, VII, and VIII. The elaborate land capability class issubsequently used to produce detailed land use function division.

The detailed land use function division commonly shows that the dominant land use function isprotected area. Protected area covers more than a half of total area. The areas are typified by very steepslope and high susceptible to landslide. On the other side, buffer and cultivated areas are mainly locatedin western part of study area. Buffer areas are characterized by moderate-high landslide susceptibleand/or moderately steep-steep slope while cultivated areas are typified by very low-low landslidesusceptibility and flat-hilly area.

The detailed land capability class has itemized the general land use function in some areas.Undulating terrain actually can be harnessed as cultivated area although the basic function of this land isbuffer area. High hill in Sidoramping lava flow is not fully apportioned as protected because some areasare suitable for buffer and cultivated area. Besides, moderate hill areas have to segregate some locationsto be allocated as protected area. The complete description of detailed land use function is summarizedin Table 6.5 and Figure 6.6.

Table 6.5. Distribution of Detailed Land Use Function Based on Proposed MethodLandform General Land

Use FunctionDetailed Land Use Function and

Width Area (Ha)

ProtectedArea

BufferArea

CultivatedArea

Volcanic cone of Lawu Volcano Protected area 2,134 - -

Lower slope of Mount Sidoramping Protected area 140 - -

Undulating terrain in lava flow Buffer area 8 215 22

High hill in Sidoramping lava flow Protected area 792 600 47

Moderate hill in Sidoramping lava flow Buffer area 204 704 -

Low hill in volcanic rock formation Buffer area 259 507 -

Small valley in Sidoramping lava Cultivated area 8 58 94

River valley Buffer area 23 90 -

Eroded volcanic cone Protected area 38 59 -

Front slope of Lawu Volcano Protected area 121 - -

Lawu lahar plain Cultivated area - 274 378

Andecite hill Buffer area - 116 -

Limestone hill Protected area 112 - -

Total 3,839 2,623 541Source: Data Analysis (2009)

6.4.3. The Comparison of Detailed Land Use Function Developed by Scoring and ProposedMethodBoth detailed methods present disparity result. The distribution of detailed land use function

from scoring method has a tendency to be concentrated in a certain part whereas proposed method isfragmented. Protected area based on scoring method is relatively agglomerated in eastern part whilstprotected areas in proposed method exist in many separated places in study area. Furthermore, bufferarea classified from proposed method is separately located in several areas. In scoring method, westernpart tends to be allocated as buffer area. The cultivated area based on scoring method exists along themiddle part of study area while proposed method puts cultivated area in western part of study area.

The differences between both methods are related to variables used. Scoring method only usesslope distribution for elaborating the general version. On the other hand, proposed method harnessesdetailed land capability class. This class is formerly obtained from comprehensive analysis of physicalland properties combined with hazard information. Nevertheless, the overall result from both methodsillustrates an advantage in developing more detail identification of land use function. The elaborate waybrings an opportunity in establishing specific and effective land use planning rather than generalversion. Thereby, the detailed result is more needed for spatial planning for comprehensively managingthe land.


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Figure 6.5. Detailed Land Use Function Map of Tawangmangu Sub District Based on Ministry of Agriculture’s Method

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Map 22Detailed Land Use Function of Tawangmangu Sub District





East JavaProvince

Protected Area

Cultivated Area

Buf fer Area

Land Use Function ClassificationRoad Class

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1. Topographic Map, Ponco l and Tawangmangu S heet,Scale 1:25,000 (2001)


Landform Boundary

River

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Province Boundary


DATUM: WGS 1984


Detai led land function wasachieved by directly overlyingthree parameters (slope, so il type, and average dai ly rainfal l

intensity). The score from each parameter was accumulatedand converted into particular land use func tion, i .e.score of <125 (cultivated zone), score of 125-174

(buffer zone), and score of >=175 (protected zone)

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Figure 6.6. Detailed Land Use Function Map of Tawangmangu Sub District Based on Proposed Method

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Map 23Detailed Land Use Function of Tawangmangu Sub District



Province Boundary




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Landform Boundary DATUM: WGS1984


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CHAPTER VIILAND USE DEVIATION IN TAWANGMANGU SUB DISTRICT

Chapter seven defines the land use deviation by identifying present land use which is not suitable withland use function. Since the land use function is developed by scoring method and proposed method;land use divergence is also observed based on scoring and proposed method. General and detailedversion is included as well. Moreover, this chapter explains the cause of land use deviation and theapplication of research result on spatial planning.

7.1. IntroductionLand use deviation can be described as inappropriateness of land use application regarding to

the zoning of land use function. Unsuitable land use practice in a certain land use function can reveal thenegative effect for the environment because the land is not used based on its capability. The negativeeffects encompass land degradation, disaster, etc. Thereby, identification process in terms of land usedeviation becomes important to avoid unpredictable situation due to incorrectness land use practice.

The land use digression is the crucial issue in land management. This information can be usedfor reforming present inappropriate circumstances. The result also acts as supporting information inevaluating the implementation of established land use function as asserted in RTRW and RDTRK.

7.2. The Suitability between Land Use Function and Land Use PracticeLand use function is a term for dividing a particular region into three functions, i.e. protected,

buffer, and cultivated area. Land use function is basically used as guidance in determining appropriateland use in a certain area. The zoning of land use function not only represents the land limitation, butalso proper land utilization and further land use application in a given area.

Each land use function is intended to a certain situation. Protected area must be kept in naturalcondition. The intensive land use practices are not allowed. Buffer area can be harnessed as cultivationzone and protected area. However, the intensity of land utilization activity is lower than cultivated areaand the activity must not disrupt the environmental balance. Cultivated area is the most appropriate landboth for agricultural purpose and built up purpose.

The regulation from Ministry of Agriculture suggests several land use practices in relation withland use function. Protected area can be applied for protected forest, preserved forest, and recreationalforest. Buffer area is possible for the following land use: limited production forest, plantation (tightcrops), and mixed garden. Cultivated area is allocated for permanent production forest, plantation (tightcrops), fruit plantation, other seasonal crops, and settlement area.

Klingebiel and Montgomery (1966) also recommend some particular land use applicationsconcerned with land capability. Cultivated area (class I - IV) is arable land which is advised to be usedfrom limited cultivated area into very intense cultivated area. Buffer area (class V – VII) is non arableland. This area is proposed as grazing area and forestry. Protected area (class VIII) shall be utilized forwildlife/natural preserve. The compatibility between land capability and land use function has beenillustrated in Table 3.8.

The suitability between land use and land use function is formed by considering the regulationfrom Ministry of Agriculture and the recommendation of Klingebiel and Montgomery (1966). Protectedarea is suitable forest, pine plantation, shrub and bush, and limestone area. The proper land use forbuffer area might be forest, pine plantation, mixed garden, shrub and bush, and limestone area. Inaddition, cultivated area can be used effectively for settlement area, paddy field, mixed garden,vegetable garden, pine plantation, forest, and also mixed paddy field with vegetable garden. Sparsevegetation in forest region is not included in suitability analysis because this land use is certainlyembedded with forest. The appropriateness between land use and land use function is completelysummarized in Table 7.1.


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Table 7.1. The Suitability between Land Use and Land Use FunctionLand Use Land Use Function

Protected Area Buffer Area Cultivated Area

Forest suitable suitable suitable

Pine plantation suitable suitable suitable

Paddy field not suitable not suitable suitable

Mixed garden not suitable suitable suitable

Mixed paddy field with vegetable garden not suitable not suitable suitable

Settlement area not suitable not suitable suitable

Shrub and bush suitable suitable not suitable

Limestone area suitable suitable not suitable

Vegetable garden not suitable not suitable suitable

Sparse vegetation in forest region - - -Source: Kliengebiel and Montgomery (1966), Arsyad (1989), Ministry of Agriculture Regulation (1980/1981)

7.3. The Identification of General Land Use DeviationThe identification of general land use deviation is aimed to obtain general description of land

use divergence in study area. The inexpediency is detected by comparing present land use and generalland use function generated from scoring and proposed method.

7.3.1. General Land Use Deviation Based on Scoring MethodGeneral land use function based on scoring method has divided the study area into protected,

buffer, and cultivated area. Eastern part of Tawangmangu Sub District is mostly allocated as protectedarea whereas western part of study area is apportioned as buffer area. The cultivated area is plotted inthe mid western part.

The comparison of general land use function and present land use practice illustrates someresults. Most of land use divergence occurs in buffer and protected area. The deviation intensity inbuffer area is bigger than protected area (Table 7.2 and Figure 7.1). Land use divergence for protectedarea is marked by the appearance of settlement area and vegetable garden. Those land uses are notpermitted to be applied in protected region. They are correctly practiced in cultivated area. Apart fromthat, the deviation in buffer area is caused by the presence of paddy field. More than one third of totalpaddy field in study area (43%) is located in buffer area. It is not suitable because paddy field asseasonal crops shall be planted in cultivation zone. The other digression cases are recognized throughexistence of vegetable garden, mixed paddy field with vegetable garden, and settlement area. In fact,32% of mixed paddy field with vegetable garden, 27% of settlement area, and 57% of vegetable gardenexist in buffer area. In addition, land use inexpediency in cultivated area is not significant. The deviationin this area is only represented by the existence of shrub and bush.

The land use deviation administratively exists in almost all villages. The worst situation occursin Blumbang and Gondosuli Village. Settlement area and vegetable garden in this location exist inprotected area. A small number of vegetable gardens also presents in buffer area. Besides, a largenumber of vegetable gardens together with settlement area and mixed paddy field with vegetable gardenin Sepanjang Village are found in buffer area. A quite similar situation as in Sepanjang Village happensin Tawangmangu and Bandardawung Village at which vegetable garden and settlement are situated inbuffer area. Land use digression in Plumbon and Tengklik Village is characterized by presence ofsettlement and mixed paddy field with vegetable garden in buffer area.

The existing land use digression ultimately describes a central problem. The problem is relatedto the presence of settlement area and vegetable garden in protected and buffer region. The developmentof settlement area in those areas is not in line with the rule from Ministry of Agriculture. This regulationstates that settlement area shall be built in cultivated area with slope of 0 – 8%. Vegetable garden is alsonot allowed in protected area. This land use is more advised to be practiced in cultivated area rather thanin buffer area. Hence, it is needed to force a better implementation of land use function as a guide indeveloping the land.


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Table 7.2. The Width Area of General Land Use Deviation Based on Scoring Method

Land UseLand Use Function (Ha)


Forest 2,908 501 8

Pine plantation 2 48 15

Paddy field - 75 101

Mixed garden - 609 43

Mixed paddy field with vegetable garden - 239 510

Settlement area 142 249 544

Shrub and bush - - 11

Limestone area - 8 -

Vegetable garden 331 454 15

Sparse vegetation in forest region 190 - -


7.3.2. General land Use Deviation Based on Proposed MethodProposed method has generally classified Tawangmangu Sub District into three land use

functions. The land use function division has been determined based on general land capability class. Asa result, protected area is allocated in eastern part. Some small areas in western part are also pointed asprotected area. Buffer area is situated in western part while cultivated area exists in mid western part ofstudy area.

The comparison between land use function and present land use identifies some land usedeviations. The divergence only occurs in protected and buffer area. The deviation in buffer area is thebiggest. In contrast, there is no land use inexpediency in cultivated area (Table 7.3 and Figure 7.2). Theinappropriate land use in protected area comprises paddy field, mixed garden, mixed paddy field withvegetable garden, settlement area, and vegetable garden. Land use digression in protected areacommonly occurs in several villages, i.e. Blumbang, Kalisoro, Bandardawung, and Gondosuli. The

Figure 7.1. General Land Use Deviation Map of Tawangmangu Sub District Based on Ministry of Agriculture’s Method

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Map 24General Land Use Deviation of Tawangmangu Sub District


Road Class

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Village Boundary

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East JavaProvince




Province Boundary

Sub-district Boundary Mixed Paddy Field andVegetable Garden

Paddy Field

Sett lement

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Buf fer Area

Land Use Function

Land Use



DATUM: WGS 1984


General land use deviation was obtained byover lying

present land use map and general land use function mapbased on scoring method. The suitabi li ty table betweenland use function and land use practice was har nessed

to recognize land use inexped iency.

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deviation in those areas is typified by the presence of settlement and vegetable garden. On the otherhand, the unsuitable land use in buffer area consists of paddy field, mixed paddy field with vegetablegarden, settlement area, and vegetable garden. Paddy field in buffer area is randomly situated at smallarea in Tengklik, Plumbon, Nglebak, and Bandardawung Village. Mixed paddy field with vegetablegarden is mostly located in Tengklik Village whilst several settlement areas in buffer area exist inTawangmangu, Bandardawung, Tengklik, and Sepanjang Village. In addition, the existence ofvegetable garden in buffer area can be recognized in Sepanjang and Tawangmangu Village.

Present land use deviation in proposed method gives a similar interesting issue as in scoringmethod. The issue is concerned with presence of settlement area and vegetable garden in protected andbuffer area. Table 7.3 illustrates that more than a half of total settlement area in study area (53%) issituated in buffer area while 28% is located in protected area. Besides, almost all vegetable gardens arelocated in protected and buffer area. Those conditions shall be given more attention since the basicfunction of those areas is not appropriate for settlement area and vegetable garden.

Table 7.3. The Width Area of General Land Use Deviation Based on Proposed Method

Land UseLand Use Function (Ha)


Forest 3,091 247 79

Pine plantation 5 60 -

Paddy field 13 83 80

Mixed garden 33 595 24

Mixed paddy field with vegetable garden 28 296 425


Shrub and bush - 11 -

Limestone area 8 - -


Sparse vegetation in forest region 190 - -


Figure 7.2. General Land Use Deviation Map of Tawangmangu Sub District Based on Proposed Method

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Map 25General Land Use Deviation of Tawangmangu Sub District





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General land use deviation was made by overlying

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land use func tion and land use practice was employed

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7.4. The Identification of Detailed Land Use DeviationThe land use function in study area has been elaborated by means of particular technique. It is

intended to obtain detailed distribution of land use function. The specified result is employed todiscover the digression land use in a certain land use function. The detailed land use deviation brings aprospect to improve existing land use function implementation.

7.4.1. Detailed Land Use Deviation Based on Scoring MethodScoring method has established elaborate land use function for Tawangmangu Sub District. The

result asserts that eastern part of study area is proposed as protected area. Western part and some areasin eastern part are apportioned for buffer area while middle part of study area has a function ascultivated area.

The evaluation between detailed land use function and land use reveals several digressions. Theland use inexpediency occurs in protected and buffer area. The intensity of land use divergence in bufferarea is much higher than in protected area. Inappropriate land use in protected area is represented by thepresence of paddy field, settlement area, and vegetable garden. Those land uses are not allowed to bedone in protected area. Apart from that, land use divergence in buffer area pervades paddy field, mixedpaddy field with vegetable garden, settlement area, and vegetable garden. Buffer area has beenpermanently used as settlement area. More than one third of settlement area is located in buffer area.The expansion settlement area is associated with the development of vegetable garden, paddy field, andmixed paddy field with vegetable garden. Detailed land use deviation is summarized in Table 7.4 and itis spatially depicted in Figure 7.3.

Table 7.4. The Width Area of Detailed Land Use Deviation Based on Scoring Method

Land UseDetailed Land Use Function (Ha)


Forest 2,357 1,007 53



Mixed garden - 612 40

Mixed paddy field with vegetable garden - 318 431


Shrub and bush - 11 -

Limestone area - 8 -


Sparse vegetation in forest region 147 43 -


Land use deviation takes place in every village. The highest intensity of land use divergence islocated in Sepanjang Village whilst the lowest intensity is situated in Karanglo Village. Land useinexpediency in Sepanjang Village is mostly caused by the presence of vegetable garden in buffer area.On the other hand, the divergence in Karanglo Village is represented by a small number of settlementsand mixed paddy field with vegetable garden. Apart from that, the major land the distribution of landuse divergence in each village is completely presented in Table 7.5.

Identification of detailed land use digression gives important information. The information isassociated with growth of settlement area and the development of agricultural activities in outside ofcultivated area. This situation cannot be tolerated since it is not in line with the existing legal regulationand sustainable concept. Therefore, local government ought to consider the strict enforcement of landuse function realization.


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Table 7.5. The Existence of Detailed Land Use DeviationBased on Scoring Method in Each Village

Village The Existence of Land Use Deviation

Protected BufferPaddyField

Settlement VegetableGarden

PaddyField

MixedPaddy

Field andVegetableGarden


Bandardawung

Sepanjang

Tawangmangu

Kalisoro

Blumbang

Gondosuli

Tengklik

Nglebak

Karanglo

PlumbonSource: Data Analysis (2009)

7.4.2. Detailed Land Use Deviation Based on Proposed MethodDetailed land use function is generated from detailed land capability class. The detailed class

considers spatial distribution of slope and landslide susceptibility. Consequently, the land use functionstend to be fragmented. The protected areas are spread out from west to east although most of thoseprotected areas are allocated in eastern part of Tawangmangu Sub District. Furthermore, buffer andcultivated areas are situated in western part of study area.

The assessment of detailed land deviation based on proposed method declares that land usedivergence exists in protected and buffer area. The number of land use inexpediencies in buffer area is

Figure 7.3. Detailed Land Use Deviation Map of Tawangmangu Sub District Based on Ministry of Agriculture’s Method

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Map 26Detailed Land Use Deviation of Tawangmangu Sub District


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Detai led land use deviation was developed by overlying

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land use function and land use prac tice was used

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higher than in protected area. The deviation in protected area is identified from the presence of paddyfield, mixed garden, mixed paddy field with vegetable garden, settlement, and vegetable garden.Besides, the digression in buffer area reveals due to the extensive development of paddy field, mixedpaddy field with vegetable garden, settlement area, and vegetable garden. The distribution of detailedland use digression can be seen in Table 7.6.

Table 7.6. The Width Area of Detailed Land Use Deviation Based on Proposed Method

Land UseDetailed Land Use Function (Ha)


Forest 2,595 740 82



Mixed garden 224 420 8

Mixed paddy field with vegetable garden 65 355 329


Shrub and bush 11 - -

Limestone area 8 - -


Sparse vegetation in forest region 117 73 -


The detailed land use deviation can be identified in each village. The inappropriate land usepractice occurs at most areas in western part of Tawangmangu Sub District. Those areas particularlyimplicate several villages, i.e. Plumbon, Nglebak, Karanglo, Bandardawung, and Sepanjang. Despitethose villages, land use inexpediency also exists in other villages located in eastern part of study area.The distribution of land use deviation in each village is summarized in Table 7.7.

The overall result of identification of land use inexpediency asserts a significant point.Improper land use practice must be controlled. It can trigger unexpected situation in terms ofenvironmental damage and disruption. Even the appropriate mechanism for conducting agriculturalactivities in a certain area is available; it is recommended that land use application is adjusted to theland capability and established land use function.

Table 7.7. The Existence of Detailed Land Use DeviationBased on Proposed Method in Each Village

Village The Existence of Land Use Deviation

Protected BufferPaddyField

MixedPaddy



MixedGarden

PaddyField

MixedPaddy



Bandardawung

Sepanjang

Tawangmangu

Kalisoro

Blumbang

Gondosuli

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PlumbonSource: Data Analysis (2009)


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7.5. The Cause of Land Use DeviationMountainous areas are characterized by six conditions. The conditions are significant

consideration in developing mountainous area. Those conditions are accessibility, fragility, marginality,heterogeneity or diversity, niche or natural suitability, and human adaptation mechanisms (Nangju inArsyad, 1992). Niche or natural suitability and human adaptation mechanism are related to responses oradaptations to the other mountain characteristics.

One of the inappropriate responses to mountainous area condition is represented byinexpediency of land use practice. The deviation is associated with human intervention in utilizing theavailable land without contemplating land capability and land suitability. The digression brings somerisks to environment, e.g. land degradation and hazard. Therefore, human adaptation to environmentshall be properly conducted.

Tawangmangu Sub District is located in south western flank of Lawu Volcano. The area istypified as mountainous region with many potencies and limitations. The potencies are related to landfertility, water availability, climate, etc. On the other side, the constraints are particularly linked withvarious topographic situation and hazard susceptibility. The existing potencies and limitations forcelocal people to establish adaption mechanisms in intensively utilizing the land to fulfill human needs.

Intensive land utilization in study area is closely related to the increasing of population number.Population growth in study area is relatively fast. It had been projected that the number of populationwill reach 47,877 people in 2016 (BAPPEDA, 2007). The increasing of population is in line with theenlarging of human needs. Doner (1987) states that population growth usually causes a growing demandfor food, wood and other raw materials, and for living space. Thus, local community tends to harnessevery possible and accessible place to meet human needs.

Intensive land use practice in Tawangmangu Sub District is also related to the economicalfunction of this area for surroundings. RDTRK of Tawangmangu 2007 – 2016 states that Tawangmanguplays a role as producer and as a collection zone of agricultural commodities. The agricultural productsare then distributed to Karanganyar City, Surakarta City, and other cities. This situation indicates thatstudy area contributes accomplishment of food crops in Tawangmangu Sub District and surroundings.As a result, this function drives rapid development of agricultural land in this area.

Figure 7.4. Detailed Land Use Deviation Map of Tawangmangu Sub District Based on Proposed Method

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Map 27Detailed Land Use Deviation of Tawangmangu Sub District


Road Class

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DATUM: WGS1984


Detailed land use deviation was made by overlying

present land use map and detailed land use function mapbased on proposed method. The suitabil ity table between

land us e func tion and land use practice was uti lized

in determining improper land use.

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Some land use practices are not always properly done. It is found some deviations in studyarea. The capability and suitability of the land are sometimes ignored. The demand of human needs andlimited space for obtaining the required need influences exhaustive land use practice in unsuitable zone.One of the crucial deviations is recognized from the development of settlement area. Ministry ofAgriculture asserts that settlement shall be located in slope of less than 8%. USDA, 1983 (in

Hardjowigeno, 1994) also establish thatsuitable area for settlement is in the slope of0 - 8%. The area with slope of 8 -15% ismoderate suitable while the area with slopemore than 15% is poor suitable forsettlement. Regarding to existing situation,more than a half of total settlement area(54.5%) is located in poor suitable zone forsettlement. Those areas exist in slope ofmore than 15% (Figure 7.5). It is only 13%of settlement area located in suitable zone.The expansion of settlement area in poorsuitable zone is probably caused by limitedarea in suitable zone.

The land use deviation cases arenot fully caused by local community’s behavior in utilizing the land. The deviation is also concernedwith the procedure in determining land use function and land use planning. Less comprehensiveprocedure gives less reliable result. The existing land capability method for land use function divisiondoes not take into account inclusive environmental parameter. It can be assumed that the result may beless accurate. As an example, some areas which some constraints (hazard probability or soil properties)are classified as productive area since those constraints are not considered yet. Therefore, thoroughinvestigation in establishing land use function and land use planning must be done.

7.6. The Application of the Result of the Research on Spatial PlanningSpatial planning in Indonesia is composed through a particular procedure. Legal Document of

Ministry of Settlement and Regional Infrastructure number 327/Kpts/M/2002 declares that nineanalyzes must be conducted to compile comprehensive information in a given area (Anonymous, 2002).The analyzes consist of strategy and development analysis, regional analysis, economic and prominentsector analysis, human resource analysis, man-made resource analysis, natural resources analysis,settlement system analysis, land use analysis, and institutional analysis.

Two of nine required analyzes are directly related to this research. Those are natural resourceanalysis and land use analysis. Natural resource analysis discusses the identification of land potency forfurther utilization in relation with land capability. The recommendation of land use function division isalso ascertained. Furthermore, land use analysis is conducted to determine the suitable land use practicefor protected and cultivated area.

Act number 26, 2007 highlights the necessity of hazard information in spatial planning(Anonymous, 2007). Hazard information becomes a major requirement to well recognize hazard pronearea. This is intended to anticipate and to minimize unpredictable damages and disruptions. Therefore,the involvement of landslide susceptibility information in establishing land capability, land use function,and further land use practice for Tawangmangu Sub District explicitly describes the appropriate way insupporting spatial planning arrangement.

RTRW of Karanganyar Regency 1997-2006 conducts three analyzes for spatial planning(BAPPEDA, 1997). Those analyzes are analysis of development policy, regional analysis, and analysisof spatial structure of Karanganyar Regency. Each analysis discusses a particular issue, as follows:a. Analysis of Development Policy discusses two topics. The topics are the function and role of

Karanganyar Regency; the status and role of sub districts in Karanganyar Regency.b. Regional Analysis consists of six important subjects. Those are analysis of physical and

environment’s support capability, demographic analysis, analysis of social community,development institution, economical analysis, and the infrastructure of social and economicalservice.

Figure 7.5. Proportion Chart of Present Settlement Area in EachSlope Class (Data Analysis, 2009)


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c. Analysis of spatial structure of Karanganyar Regency concerns with the settlement system,identification of priority region, and land use function and development trend.

RDTRK of Tawangmangu 2007 – 2016 also presents several regular analyzes (BAPPEDA,2007). Those analyzes are grouped into macro analysis and micro analysis. Macro analysis comprisesregional constellation and the relationship with surrounded area. Moreover, micro analysis encompasses13 important analyzes. Those are physical basic analysis (physical analysis and the analysis ofenvironment’s support capability), land use and building analysis, demographic analysis, economicalanalysis, spatial analysis, transportation system analysis, infrastructure analysis, utility, assessmentanalysis of service center, analysis of spatial planning structure, building parcel analysis, hot spotanalysis, and tourism analysis.

Land capability assessment and land use function division in RTRW are conferred in theanalysis of physical and environment’s support capability. Land capability assessment in this analysis isgenerated by using five variables, i.e. slope, soil depth, soil texture, drainage, and erosion. Land usefunction is developed through Ministry of Agriculture’s method (scoring method). On the other hand,land capability assessment RDTRK is explained in the analysis of environment’s support capability.This assessment is intended to the land use function in Tawangmangu. The land capability appraisal isdone by scoring method. Thus, it is proved that the result of this research can be involved within certainanalysis in spatial planning process. The proposed method from this research can be utilized to improvethe existing method.


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CHAPTER VIIICONCLUSIONS AND RECOMMENDATIONS

This chapter explains some brief conclusions and recommendations. The recommendations areparticularly intended for future research and further usage of method harnessed in this research.

8.1. ConclusionsThis research gives some valuable results concerned with the research objectives and questions.

The results are summarized into following conclusions. Landslide susceptibility analysis asserts that 43% of total area is classified as moderate susceptible

whereas 42% is categorized as high and very high susceptible. The result also shows that more thana half total settlement area is situated in moderate susceptible while 35% is located in high and veryhigh susceptible. Regarding to the extent of settlement area in landside susceptible zone, the somemitigation strategies are also proposed to minimize the impacts.

Land capability assessment generally classifies the study area into class IV, VI, VII, and VIII. Thegeneral classes are overlaid by slope and landslide susceptibility to define detailed land capabilityclass. The result illustrates that one general land capability class can be specified into several landcapability classes. Detailed land capability class for study area consists of class III, IV, V, VI, VI,and VIII.

Land use function based on scoring method generally demonstrates that the range of score is 90 –195 in which 51% of total area is protected area; 31% is buffer area and the rest is cultivated region.Besides, detailed version gives score range 70 – 195 in which 38% is assigned as protected area;45% and 17% is apportioned as buffer and cultivated area respectively. On the other hand, generalland capability class based on proposed method allocates 58% of study area as protected area; 31%as buffer area and 11% as cultivated area while detailed method assigns 55% of study area asprotected region, 37% as buffer region, and 8% as cultivated region.

General land use deviation based on scoring method states that the inappropriate land use practicecan be found in all land use functions. Land use deviation in buffer area is higher than in protectedand cultivated area. Land use deviation in buffer area is represented by the appearance of paddyfield, mixed paddy field with vegetable garden, settlement, and vegetable garden. Besides, there aresome inappropriate land use practices in protected area, i.e. settlement, and vegetable garden. Apartfrom that, proposed method declares that land use divergence in buffer area is much higher than inprotected area. There is no land use deviation in cultivated area. The most land use inexpediency inprotected area consists of vegetable garden and settlement. Land use divergence in buffer area canbe identified based on the existence of paddy field, mixed paddy field with vegetable garden,settlement, and vegetable garden. On the other side, detailed version of both method shows thatthere is no land use divergence in cultivated area. Land use digression in buffer area is also muchhigher than protected area. According to scoring method, unsuitable land uses in protected andbuffer area are paddy field, settlement, vegetable garden, and mixed paddy field with vegetablegarden. Furthermore, proposed method identifies some inappropriate land uses in protected andbuffer area, i.e. paddy field, mixed paddy field with vegetable garden, settlement area, vegetablegarden, and mixed garden. The existing land use inexpediency appears as a consequence of theincreasing of human intervention to the environment. It is related to the enlarging of human needs(food, space for living, etc.). Exhaustive land utilization shall be managed in order to minimize thefuture risk, especially associated with landslide threat.

Land capability assessment based on USDA approach is able to support the decision in dividingland use function. The choice either general or detailed version can be applied. The detailed versionwill present the elaborate result. The involvement of landslide susceptibility information is alsouseful to reveal more comprehensive result.

8.2. RecommendationsThe research has been done to integrate landslide susceptibility information in assessing land

capability. The findings during the research are used to make some recommendations for betterresearch. The recommendation about implementation of spatial plan is also proposed. Thoserecommendations are mentioned below: The landslide susceptibility method in this research is possible to be used in every administrative

level. The established weight and score can be adapted or modified depending on the scale and


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purpose. It is recommended to compile more specified data, particularly related to soil properties, inorder to get better result and precision. The minimum required data for generating landslidesusceptibility information are presented in this research. Therefore, future research can involveother variables, such as rainfall, lithological structure, earthquake, etc.

Proposed land capability assessment can be utilized as an alternative way in determining land usefunction. The contribution of landslide susceptibility information in this method meets therequirement of Act number 26, 2007. This method can be also applied to enhance present landcapability analysis. The method is applicable on two analyzes in spatial planning process, i.e.natural resource analysis and land use analysis. To improve the result, all variables in landcapability assessment shall be fulfilled. Those are slope, erodibility, actual erosion, soil depth, soilpermeability, soil texture, soil drainage, and rock fragment. Hazard information can be adjustedwith common hazard characteristic in a given area. In addition, soil survey to obtain requiredinformation is recommended to be elaborate conducted. It is intended to get more comprehensiveresult about existing constraints.

Land use function division shall be clearly defined in the field. Some warning signs and landallocation maps can be constructed in order to disseminate land use function division. Localcommunity is guided to use the land based on its function.


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Anonymous. 1981. Criteria and Procedures in Determining Productive Forest, Legal Document ofMinistry of Agriculture number 683/Kpts/UM/8/1981http://penataanruang.pu.go.id/ta/Lapak04/P3%5CDASbatanghari%5CLAMPIRAN%202.pdf(26 May 2009, 07.11 pm).

Anonymous. 2002. Procedures of Province Spatial Planning Arrangement, Legal Document of Ministryof Settlement and Regional Infrastructure number 327/Kpts/M/2002,http://www.penataanruang.net/taru/nspm/7/Bab4.pdf (26 May 2009, 06.52 pm).

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BAPPEDA (Development and Planning Board) of Karanganyar Regency. 2007. Rencana Detail TataRuang Kawasan Pengembangan Kota Tawangmangu, Kabupaten Karanganyar 2007 – 2016(Detailed Spatial Plan of Subdistrict City of Tawangmangu 2007 – 2016). BAPPEDA ofKaranganyar Regency: Central Java.

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LIST OF APPENDICES

1. Field data

2. Soil type map and slope map based on Ministry of Agriculture’s method

3. Monthly rainfall intensity

4. Documentation of field work activity


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Appendix 1

Field Data

No Coordinate SoilDepth

Soil Texture SoilPermeability

Soil drainage RockFragment

Latitude Longitude Very FineSand

Sand Silt Clay Texture

1 520530 9152857 > 90 52,05 55,29 25,65 19,06 Sandy loam 73,73 well no

2 519585 9152904 > 90 42,47 43,81 35,93 20,26 Loam 2,83 well no

3 518281 9153373 > 90 49,62 50,74 31,88 17,38 Loam 15,26 well no


6 516658 9153409 > 90 46,94 48,87 30,96 20,16 Loam 0,07 well no

4 520111 9152173 > 90 41,36 41,78 48,19 10,02 Loam 25,81 well no


8 513629 9152972 > 90 43,92 46,07 31,45 22,47 Loam 17,56 well no


10 519779 9151354 > 90 49,9 50,60 31,01 18,39 Loam 67,87 well no


12 515857 9151749 > 90 53,34 57,31 21,62 21,06 Sandy clay loam 32,3 well 15 - 50%

13 514985 9152529 > 90 45,88 46,28 29,25 24,47 Loam 8,28 well no

14 516828 9152710 > 90 51,1 52,20 29,76 18,03 Loam 18,48 well 15 - 50%

15 514330 9151144 > 90 25,14 26,47 39,58 33,95 Clay loam 7,58 well no

16 513710 9151377 > 90 29,28 32,30 30,52 37,18 Clay loam 0,07 well 15 - 50%

17 513063 9151328 > 90 21,87 22,53 27,45 50,02 Clay 18,82 well no

18 512212 9150762 > 90 15,91 17,21 27,06 55,73 Clay 15,52 poorly no

19 511675 9151529 < 25 16,94 18,34 30,64 51,01 Clay 0,18 poorly > 90%

20 511081 9150956 25 - 50 16,8 17,82 27,61 54,56 Clay 60,43 well no

21 511073 9154867 50 - 90 37,26 40,12 32,79 27,09 Clay loam 4,06 well 15 - 50%

22 512851 9154161 > 90 22,22 23,66 29,88 46,46 Clay 2,31 well no


24 511618 9155310 > 90 11,16 11,56 50,68 37,76 Silty clay loam 3,53 well 15 - 50%

25 511977 9154014 > 90 20,3 21,83 33,72 44,45 Clay 0,93 well 15 - 50%

26 516440 9151535 > 90 48,84 52,25 32,23 15,52 Loam 9,81 well 15 - 50%

27 511487 9153590 > 90 28,99 31,67 36,55 31,78 Clay loam 0,14 poorly no

28 514288 9154616 > 90 42,6 45,43 33,06 21,50 Loam 8,31 well no

29 512500 9152836 > 90 48,02 50,19 38,24 11,57 Loam 13,62 well 15 - 50%

30 508437 9152760 25 - 50 24,65 25,75 41,31 32,94 Clay loam 4,68 poorly no

31 510003 9152920 > 90 37,17 40,22 35,42 24,35 Loam failed poorly no

32 510710 9152543 > 90 28,38 30,17 41,97 27,86 Clay loam 1,13 moderately well no

33 511215 9152477 < 25 44,52 48,78 29,96 21,26 Loam 5,85 poorly > 90%

34 508421 9152477 < 25 29,87 32,88 31,39 35,73 Clay loam 1,85 poorly 50 - 90%

35 509989 9152393 < 25 37,45 41,51 21,77 36,72 Clay loam 1,52 excessivelly > 90%

Source: Field Work and Soil Laboratory Analysis (2009)


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Appendix 2

Soil Type Map of Tawangmangu Sub District

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Map 28Soil Type of Tawangmangu Sub District

Soil Type

Brown Andosol

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Yellowness Brown Andosol


Province Boundary

Seasonal River

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Landform Boundary




East JavaProvince

DATUM: WGS 1984


Soil type information was tak en fromsoil map. The soi l typewas adjusted byexisting landform in study area.

The map was completed by some additional infor mation

(river network and adminis trative boundary). N

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Slope Map of Tawangmangu Sub District Based on Ministry of Agriculture’s Method

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International Institute for Geo-Information Scienceand Earth Observation (ITC), The Netherlands Map Created by: Sri Eka Wati (08/276590/P MU/5638)

DATA SOURCE:

LEGEND:

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Map 29Slope of Tawangmangu Sub District


Slope Class

0 - 8% (Flat)

8 - 15% (Slightly Slope)

15 - 25% (Moderately Steep)

25 - 40% (Steep)

> 40% (Very Steep)

Landform Boundary

Province Boundary





East JavaProvince

River

Seasonal River1. Topographic Map, Poncol and Tawangmangu S heet,

Scale 1:25,000 (2001)


DATUM: WGS 1984


Slope map was der ived from contour l ine. The contour wasconverted into raster format. It was then pr ocessedby using slope tool in ArcGIS. Slope was classified

based on Ministryof Agricultu re's slope classif ication.N

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Page | 91

Appendix 4

Documentation of Field Work Activity

Interview Session with Staff of BAPPEDALand Use Observation from Limestone Hill

Soil Depth Measurement inSoil Survey

Identification of Soil Structure(The Picture Depicts Blocky

Structure in Study Area)

Identification of Yellow Spot inthe Soil as a Description of Soil

Drainage Condition

Yellow Spot

Documents

Thesis Sri Eka Wati 1b 19jan - Universiteit Twente · 2010-04-29 · Sri Eka Wati 08/276590/PMU/5638 AES-22612 Supervisor: Dr.rer. nat. Junun Sartohadi, M.Sc (UGM supervisor), Gadjah